sph3u+old

**SPH3U Homework - 2012-2013**
timeline (see main page), Grading policies (most consistent, most recent, lates/zeros) Homework policies, quizzes, chapter assignments Some key ideas in physics Outline of first unit -motion - calculation of speed ( = distance / time) - standard units for distance (m, km) time (sec, hr) and speed (m/s and km/hr) - difference between speed (scalar - just a number) and velocity (vector - also has a direction) Introduction to lab 1 - Carts and Collisons (Thursday) || given info formula substitution answer with correct units || Handout of setup and measurement suggestions - this may make your life easier, but who knows?? When finished, calculate the average for each trial so that you have 4 excellent data points per lab section || Enter your data into a spreadsheet so that we can look at analyzing the data next class || My focus is on your method, not just the answer, since these are relatively easy problems. However, the same method will work even when the problems are more difficult. Lab Analysis - what is required for the graph, correlation and relationship How to use spreadsheets to make your life easier! ||  || - standard units, converting between m/s and km/hr, vectors vs scalars - distance (scalar) vs displacement (a vector) = actual path vs shortest path from start to finish - speed (scalar) vs velocity (a vector) = dist / time vs displ / time velocity ≤ speed and displacement ≤ distance both velocity and displacement need a direction, since they are vectors average speed = total distance / total time average velocity = displacement / total time Second half of the class in the computer lab - work on finding an equation that best describes your data - we expect the relationships to be linear, quadratic, or a power function (rational or root) - Excel can add a trendline to your graph and indicate how close it matches the given data: if the R² value is 1, the trendline matches the data perfectly. || Lab due Thursday at beginning of Math Class.
 * **Today's Date** || **Class Topics and Summary - First Semester** || **HandoutsAndHomework**
 * [[file:NelsonTextAnswers.pdf|Nelson Textbook Answers]]** ||
 * Sept 4 || How to succeed in this course - course syllabus and
 * 1) 28-32
 * Sept 6 || Carts and Collisions lab - starts in Math class, continues in physics
 * Sept 7 || Take up problems 28-32 from homework (answers are 45 m, 39 m/s, 14 m/s[E], 267 s, 997 m
 * Sept 11 || First half of class - review of homework problems:

for Thursday p 54 # 46-48 46 - 2 m/s [E] 47 - 20.83 m/s [N] 48 - 19.17 m/s [W] Make sure you give your online book registration sheet to Mr Guetter || Speed - bus jump scene - [] [] Speed - jump footage - []
 * Sept 13 || Introduction to motion - motion in a straight line

Rules for significant digits - how accurate should my answers be?? 1. in general, one or two decimal places is plenty 2. specifically, no answer can be more accurate than the least precise number in the calculation Calculations of distance vs displacement and speed vs velocity - displacement and velocity are both vectors - measured "as the crow flies" - vectors include a direction, which is a rotation from North (0 or 360 degrees) || || Review of distance vs displacement and speed vs velocity - vector problems involving oblique triangles. Ex: car travels 60 km west and then 40 km north-west (315º), in a time of 1.5 hours. Calculate the distance, displacement, speed and velocity of the car. I want you to draw a (scale) diagram, but don't take your answers from the diagram; use the diagram to confirm your algebra and trig work Two options for adding vectors: - use the laws of sines and cosines - use vector components of right triangles - the textbook uses this approach || HW - a ship travels 35 km @ 130º, then 10 km @ 220º, and finally, 15 km @ 90º, in a time of 2.5 hours. Calculate the displacement and the velocity
 * Sept 14 || **Quiz next class** on first set of problem solving, some definitions/comparisons, units and unit conversion, vectors and scalars

answer: 46.5 km @ 130.5º || Monty Hall problem - as an introduction to Friday's activity on probability. Try [|this link] if you need to convince yourself that switching is always best. Review of using components to solve vector addition problems (displacement and velocity) additional practice problem: use components to solve the following: travel 100 km @ 290º, then 120 km @ 80º, finally 80 km @ 150º Last year's answer 65.77 km @ 102.5⁰ Quiz on first few topics - motion, calculations, vectors - remember that quizzes are a chance for you to find out what you know and where you need to work. Quizzes NEVER count against you; in fact, they may even help your mark if they show a better understanding than your end-of-unit tests/projects/etc. || || Have you tried the "Let's Make a Deal" simulation yet? Who has a good mathematical or logical explanation? Instantaneous Speed - how do we measure the speed of an object when the speed is constantly changing - like in real life?? - if you are given a graph, draw a tangent line to the graph AT THAT POINT and measure the slope of the line - a tangent line is a line that touches a curve in exactly one spot (over a short distance). The handout in class shows how to calculate the slope (speed) at 5 points along a distance vs time curve. For the slope of tangents on distance-time graphs: - don't count squares - don't measure with a ruler - use the scale on the x and y axes If you are given a table of data, you will have to take the slope between points that are near the point in question ||  || Problem: If we roll 12 dice, there is a really good chance (probability) of getting two 3's. However, we don't expect to get two 3's on each roll, do we? But what about over the long run? Like when we have rolled 12 dice a hundred or more times? Do we expect that over the long run 1/6 of the dice will be 3's? We will investigate this as a group in four or five activities that involve collecting data on random occurrences - rolling dice, flipping coins, drawing cards, selecting consonants or vowels, etc. Each one of you will then take a complete set of data and prepare a graph that compares the number of trials vs the percent that were successful (ie: if you need "tails" you got tails). And hopefully, by the end of this exercise, you will see that probability really works. || [|probability]
 * Sept 18 || Connection between math-functions and physics: given points on a parabola (either horizontal distance vs height or time vs height) find the equation of the parabola that best matches the data. We found the A-values to be -2/75 and -3/2.
 * Sept 20 || Quiz 1 due by end of the day - that way I can return it to you tomorrow.
 * Sept 21 || Lab - using multiple trials to confirm expected values.

I suggest using a GoogleDocs spreadsheet so that you can share data easily. I expect ONE GOOD report per group. || login details - please change your password New Unit - Accelerated motion - how to describe the motion of an object that is speeding up or slowing down, both with graphs and with equations. ||  || Review for Test - bring any questions to class - practice of dist-rate-time problems, vector problems (displacement vs distance, velocity vs speed) - format for test - multiple choice or true/false (10 pts), fill in the blank (5-10 pts), graphs (10 pts), problem solving (20 - 25 pts) Calculation of Acceleration - formula, slope formula, rise/run, delta notation d = v * t v = (vi + vf) / 2 a = (vf - vi)/t = Δv / Δt || Work on first five acceleration problems from - remember to work in m, sec, m/s and m/s² ||
 * Sept 25 || Quiz # 2 available at [|www.classmarker.com]
 * Sept 27 || Only 7 students did the online test - what's going on??? skipping quizzes is a poor choice.
 * Sept 28 || Test on Unit One ||  ||
 * Oct 2 || Walk-a-thon ||  ||   ||
 * Oct 4 || Check problems 4 and 5 from the accelProbs handout - you need to work with two different formulas in each problem. In number 5 you need to use elimination or substitution to solve 2 equations with 2 unknowns.

Solving problems using average speed for acceleration problems - this method works, but perhaps there is a better way? What if we combine some of the formulas from last class? Kinematic formulas for acceleration problems: we will use: vf = vi + at d = vi t + ½ a t²  vf² = vi² + 2ad d = vf t - ½ a t² || 35 - 39, 42, 51 must start each problem with a formula, then substitute ... || 1. The general shape for distance vs time (accel vs decel) 2. The general shape for speed vs time for (accel vs decel)
 * Oct 5 || Graphs for distance and speed of an object with uniform acceleration:

Your homework is to complete the TWO data tables and FOUR graphs from the handout: a v-t and d-t graph for an accelerating object and a v-t and d-t graph for a decelerating graph. Answering the questions should be easy once you have the table and the graphs. || || 1. Review of general shape for acceleration and deceleration - always need to get general shape correct and label (at least) one non-zero point 2. Another way to find the distance an object travels while accelerating or decelerating is to calculate the area enclosed by the speed-time graph. The area can usually be divided into rectangles and triangles, and we can calculate those areas easily. 3. Introduction to video analysis of projectile motion - [|Tracker Software] In the next activity you will use a video camera to record and analyze the motion of a projectile - I will show you how the software works today, have you pick an activity next class, and gather the video footage and begin analyzing data on Friday. The final product will be a **class presentation** by your group of four students. || Ch 1 # 40, 55, 56, 57 || Video each group with at least three different projectile paths ||  || Acceleration - solving acceleration problems using algebra || || To find the time when the speeds are the same, we get two equations for Vf (one for police, one for motorcycle); then we substitute and solve for time; then we can solve for Vf, the speed. To find the time at which the distances are equal, we get two equations for d (using vi t + ½ a t² - one for police, one for motorcycle); then substitute and solve for time; then solve for d, the distance. Finish off the handout. || || Accel 3 Ways handout - lays out each of the methods for determining the distance covered - and you get to practice each one. Calculations involving gravity g = (-) 9.8 m/s². Since "g" always points downward, we need to be careful when solving problems in which the initial speed is upward. Remaining time is to finish off the written quiz, to finish the algebraic problems, and to start the online quiz for this unit || || Online quiz for acceleration (test on Tuesday, Nov 6) **Introduction to the Amber light problem** - this is just another application of the kinematic equations, but it relates to a very specific problem area for new drivers. The question in its simplest form is this: when the light turns yellow, can I safely stop OR safely go through the light? Or will I be in trouble if I choose the wrong option here? The amber light problem can be solved by using a number line to indicate two regions: a region in which it is safe to continue at the current speed, and a region in which it is safe to stop (including both the reaction and stopping distances). The safest intersections have overlap between these two regions - that is, there is a region in which you can either safely stop or safely go, so it doesn't matter which one your choose. For example, if the light is yellow for 4 seconds, your speed is 80 km/hr (22.2 m/s), your reaction time is 1 second, and your deceleration rate is (-) 5m/s², you should be able to calculate the following: - min distance to make it through at current speed = 88.9 m (for any distance < 88.9 m, you can continue) - reaction distance before braking = 22.2 m + distance while stopping vf² = vi² + 2ad gives 49.3 m for a total of 71.5 m So ... you can brake if you are more than 71.5 m away and you can stop if you are less than 88.9 m away, which gives a transition (or safety) zone of 17.4 m.  In the transition zone, you can either go through at the current speed OR safely stop; it doesn't matter which one you choose - both are right. And safe. And you can nicely draw this on a number line: || before next class do this quiz [|Accel Quiz online]
 * Oct 9 || Final due date for probability lab to be handed in.
 * Oct 11 || Planning / Design for data collection and analysis
 * Oct 12 || Lab Analysis - use Tracker software to import the video, set the scale and origin, and track the object position frame by frame. The data will allow you to create three different graphs for the three throws: one of height vs time, one of horizontal distance vs time, and one of height vs horizontal distance. Mr Hunse can show you how to arrange the x-y data for the third set of graphs. In each graph, you will have THREE sets of x-y data. We will present this lab in groups on Oct 23. ||  ||
 * Oct 16 || Video of Felix Baumgartner's free-fall from near space - and the connection to d vs t, v vs t, and a vs t graphs, only given a = 9.8 m/s² and vf = 1170 km/hr (before opening parachute).
 * Oct 18 || Take up algebraid problem #1 using equations for Vf and D. Here are the graphs: [[file:carPoliceVT.JPG|v-t]] [[file:carPoliceDT.JPG|d-t]]
 * Oct 19 || Three ways of calculating the distance covered while accelerating - graphs, average speed, and kinematics formulas
 * Oct 23 || Presentations for projectile motion - each group presents their findings on the projectile lab -[| here] is the marking scheme, which you already have - Only two groups presented today, what's up with that?
 * Oct 23 || Presentations for projectile motion - each group presents their findings on the projectile lab -[| here] is the marking scheme, which you already have - Only two groups presented today, what's up with that?

|| -if we continue at the same speed, we use the formula for uniform motion: d = v*t -if we decelerate, we divide the problem into TWO parts: the reaction time (in which the speed remains the same) and the stopping distance, which is solved using vf² = vi² + 2ad. The reason we use the equation for vf² is that this gives the total distance required to stop, even if it takes longer than 3, 4.5, or more seconds. Plugging t and a into the distance formula just tell us how far we travel in a certain time, but doesn't tell if we have actually stopped in that distance. Again, I'm not accounting for the third option - speeding up when the light turns yellow - because I don't want to be the reason you start driving aggressively. I'll let someone else do that... Part 2 of the problem, using the same reaction time and the same deceleration rate: If you are traveling 60 km/hr and are 50 m from the intersection when the light turns yellow (3 seconds) -what should you do? can safely stop or continue -how large is the safety zone for this amber light? 50.1 m if you continue, 44.5 m required to stop, so the safety zone is only 5.5 metres, which is about 0.3 seconds at a speed of 60 km/hr. In the previous problem, the safety zone is about 17.4 m, which is 0.8 seconds (or so) - a much longer time. || Finish the second side of the amber light handout for next class.
 * Oct 30 || Review part 1 of the amber light problem. In terms of the calculations, here are the basics:

Several of you have already completed this [|quiz 2 Online] Please take advantage of opportunities to take quizzes since they help you to learn. || Review problems for algebraic problem solving, yellow light problem, calculations and graphs for accelerated motion. We will continue working through these problems tomorrow, when a number of you are gone. Test date - Tuesday, Nov 6 ||  || The test will consist of four multi-step problems - acceleration problem that includes graph of dist-time or speed-time, algebraic motion problems - one object speeding up and one slowing down, the yellow light problem, something involving projectiles and gravity. You will be given all the formulas. || || Introduction - river crossing and airplane problems Begin new unit on vectors and motion - using vector addition to account for the motion of a medium in which an object is moving. Introductory videos: [|river crossing] [|airplane] Ex: Boat heads directly across a river while the current pushes the boat downstream. Can we calculate the actual speed of the boat and predict where and when it will reach the opposite shore? Ex: An airplane wants to go directly north, but there is a wind blowing from the west. At what angle should the plane head to compensate for the wind and what will its speed be? Two dimensional motion problems can be solved by adding vectors - a tutorial to get you started is [|here] here are links to visual examples [] [] || || 1. if you do not account for the moving medium, the medium pushes us along and we end up off course. 2. if you take the moving medium into account, you need to compensate for it to stay on course. In both cases, you need to use trigonometry to solve for speeds, distances, and headings. In most cases, we deal with right angled triangles; however, you will need to use the law of sines or law of cosines from time to time as well. Two examples for today - these are harder than the typical problems, so if you can solve them, you're fine! 1. An airplane flies on a heading of 285 degrees at 600 km/hr but is affected by a wind blowing north at 60 km/hr. Find the actual velocity (speed and heading) of the plane. 2. A boat can travel 5 m/s and a river flows north at 2.5 m/s. The boat needs to cross a river that is 300 m wide, from west to east, and end up 50 m upstream from where it started. Find the heading that the boat needs to take so that the current pushes the boat on the correct course. || Do two problems from the last page of the handout - #37-42 - one boat problem and one airplane problem. || Today - work through vector problems from the handout Finish by watching [|this video] on Rube Goldberg machines || inish vector problems from handouts - most of these are right angle problems. || A few things to take away from the discussion: - there are many different methods of determining the approximate age of a substance - the best or most reliable results occur when two different methods give the same result - the principle of uniformitarianism has strengths and weaknesses to it - radioactive decay curves all have the same shape; the difference is in the time scale - hundreds, thousands, millions, billions. And that's where some of the debate is. - I am convinced that the Bible and the world tell us the same things about God and the creation; I am committed to believing the Bible and honouring the results of scientific inquiry. I think we run into problems when we force one to match the other - see [|Article 2 of the Belgic Confession] || || New problem - boat heads upstream at 4 m/s at angle of 20 degrees, if the current pushes the boat downstream at 2 m/s, find the actual speed of the boat, the time to cross the 100 m wide river, and the distance you end up downstream. (3.8 m/s, 26.6 sec, 17 m) And another variation: boat and current speed are the same as above, river is 100 m wide, but now we want to land exactly 40 m downstream. At what angle do we aim the boat (relative to directly across)? (law of sines gives 27.6 degrees, so the answer is 6 degrees upstream from straight across) - four fundamental forces (strong, weak, electric, gravity) these forces decrease in strength (from left to right), but increase in distance over which the force operates - this means that the strong force (which holds the atomic nucleus together) is incredibly powerful, but it only operates over very short distances; gravity is the weakest force, but it can operate over incredibly large distances - Newton's second law: an unbalanced force applied to an object will accelerate the object in the direction of the force. - this gives rise to the equation f = m*a where force is in Newtons, mass in kg and a in m/s² Gravity - the calculations used for gravity depend on whether the object is near the Earth or nowhere near the Earth. - if the object is near the Earth, we calculate the force with f = m*g where g is the gravitational field strength near Earth ( = 9.8 N/kg) - if the object is not near the Earth, we need to use a more general calculation (Newton's law of universal gravitation) || P 67 # 1-4 P 70 # 12-18 from Nov 8 handout || 1. Inertia - an object at rest remains at rest and an object in motion remains in motion, unless acted on by an unbalanced force 2. Acceleration - an unbalanced force causes an object to accelerate in the direction of the force 3. Reaction - all forces act in pairs that are equal and opposite; for every action there is an equal and opposite reaction Preparation for Friday's presentation by Ross McKitrick - look at two documents: [|Ontario Air Quality Report - 2010] [|The Devil is in the Generalities] ||  || - is the Earth a china shop or a playground? The language of the environmental movement is one of china shop, but history (and especially history of environmental disasters) shows that the Earth is much more robust than we think. - what does the data say about climate change and environmental pollution? - we need to develop a theology of creation use and creation care - Earth and its resources are to be **used**, in service to God and others; humans are the **crown** of creation, not just one of many competing inhabitants of the Earth. ||  || We agree to call any reaction force provided by a surface the NORMAL force = Fn. This is to balance the force of gravity on objects, for example, when a coffee cup is at rest on a table. There are two forces, Fg and Fn, and they point in opposite directions Newton's laws - review of the three laws, with focus on the second law. If an unbalanced force acts on an object, the acceleration is given by f=m*a, where m is the mass of the object, f is the force (push or pull) in Newtons, and a is the acceleration in m/s². || p 142 # 1-3 p 144 # 18, 20 || Review of free-body diagrams. We draw an object as a dot and label all forces as vectors. We use a simple notation for common forces: Fg for gravity, Fn for the upward force that opposes gravity, Ffr for friction, and so on. We learned that there is a connection between the force applied to an object and the acceleration that a mass experiences - and this is given by Newton's second law: Fnet = m * a || P 142 Q 6,7,8 p 144 Prob 21,22 || Review of Free-body diagrams, net force, acceleration, and kinematic calculations - the force of gravity on an object is given by Fg = mass* g, where g = 9.8 N/kg or m/s² - draw FBD, calculate net force, solve kinematic problems. p 144 # 29-31 || - if the object is near the Earth, we calculate the force with f = m*g where g is the gravitational field strength near Earth ( = 9.8 N/kg) - if the object is not near the Earth, we need to use a more general calculation (Newton's law of universal gravitation) Fg = Gm1m2/d², where m1 and m2 are the masses (in kg), d is the distance between the centres of the objects (in m), and G is the Universal Gravitational Constant: 6.67 x 10 -¹¹ N m²/kg² Homework - calculate the force of gravity on a 20 kg object resting on the surface of the Earth in TWO ways: 1. use Fg = m*g to get 196 N 2. use the mass of the object, the mass of the Earth 6x10 ²⁴ kg, distance between the centre of the Earth and the object = 6400 km. Make sure your calculation uses only standard units (m, s, kg) - verify that you get an answer of about 196 N with this calculation. It is interesting that both calculations give the same results. However, Newton's formula is more useful since it allows us to calculate the force of gravity between ANY two objects anywhere in the universe. THEN do two more calculations: determine what happens to the force of gravity between the 20 kg mass and the Earth if -the distance is doubled (to 12800 km) -the distance is reduced to one-third of the original (2133 km) I will show how you can use ratios or proportions to solve this more simply than using Newton's LoUG; however, Newton's calculation will always work (it just takes more effort sometimes) || we did this with a 20 kg mass, but the idea is the same regardless of the mass. [|Fg handout answers] || - if the object is moving, relative to an original position, you can use proportions - Fg is proportional to 1 / d². This means that if the distance doubles, the force is reduced by a factor of FOUR; if the distance is one-third of the original, the force is increased by a factor of NINE. - we can set up this using ratios, as shown in class: Fg1 / Fg2 = d2² / d1² - what's interesting is that we don't need to know the actual distances between the objects; we just need to know the ratio of the change in distances (ie: how much does the force of gravity increase if the distance between two objects is 1/4 of the original amount? we can use any two numbers that are in the ratio of 1:4 and we know that the increase will be a factor of 16) ||
 * Nov 1 || Remaining presentations for projectile lab - any groups not prepared will be evaluated individually, during lunch or spare.
 * Nov 2 || Review of acceleration unit - test next class - Nov 6
 * Nov 6 || Test - whole class ||  ||
 * Nov 8 || Last motion topic - motion in two directions. While our textbook covers projectile problems in this unit, I save that for grade 12, when you have more experience with vectors.
 * Nov 13 || Review of introductory concepts:
 * Nov 15 || Take up homework problems with vectors - keep in mind that we are (usually dealing with one of two questions): If we don't account for the wind or current, where do we end up? How do we adjust the heading so that we fully compensate for the wind or current?
 * Nov 16 || Connection to math class - exponential growth and decay = radiometric dating
 * Nov 20 || Today we finish the vector problems
 * Forces Introduction**:
 * Nov 22 || Review of forces - introduction to Newton's three laws of motion
 * Nov 23 || Presentation and Q&A session with Ross McKitrick - University of Guelph, Economics Department
 * Nov 27 || Free-body Diagrams - a dot that represents an object; arrows represent the vectors (forces, in this case). The goal is to reduce a problem to an object with ONE FORCE in ONE DIRECTION.
 * Nov 29 || Forces - answers the question "what causes things to move" clip from "Chuck" - []
 * Nov 30 || Take up homework - special focus on question 8 - the horse can move the cart, not because it pulls harder on the cart, but because it pushes harder against the ground than the cart does. Just like your team wins the tug of war because it pushes harder against the ground than the other team. || P 144 # 23,25, 26,27,28 ||
 * Dec 4 || Test Date - Tuesday, Dec 18. Topics: 2-dim motion, Newton's laws, forces, acceleration, gravity
 * for objects accelerating upward, we must always account for gravity in determining the net force
 * air resistance is not a constant amount; in general, it increases as the speed of an object increases, to the point where the air resistance equals the downward force of gravity (terminal velocity). You can see this more clearly if you drop a rock in water. || [[file:FBDkinematics.pdf|handout]] # 1-6
 * Dec 7 || Force of Gravity - the calculations used for gravity depend on whether the object is near the Earth or nowhere near the Earth. Scientists haven't quite untangled the question of why gravity exists or why objects with mass have gravitational attraction, but recent experimental results point toward the "Higgs Field". It is helpful to think as gravity as a depression, curvature, or density change in space that causes other objects to move toward it. I will demonstrate this with the tablecloth used for the "who likes magic?" demo.
 * Dec 11 || Third way to solve force of gravity problems:

P.110# 12, 15-22 || Review for Test: 2 problems on airplane/river problems, one with non-right-angled triangle 1 problem and 1 short answer question on force of gravity and Newton's law of universal gravitation 2 problems and 2 short answer questions on forces, FBD, Newton's laws of motion ||
 * Dec 13 || Review of Vectors, Newton's Laws of motion, free-body diagrams, calculations of force, mass and acceleration, connection to the kinematic equations, calculations of gravity using "g", Newton's law of universal gravitation, and proportions.

C-3 the answer is 612.5 N, not 1089 N || Law of conservation of energy - two statements 1. Energy is neither created nor destroyed; it just changes from one form to another (generally less useful forms). 2. The sum of potential and kinetic energy in a closed system is a constant.
 * Dec 18 || Test on Forces, Newton's Laws of motion, and gravity calculations - whole class ||  ||
 * Dec 20 || Introduction to Energy, Work and Power - [|Rube Goldberg Machines]

However, in the real world, energy transformations almost always result in less useful forms of energy. We refer to this as "entropy". Take the example of a litre of gasoline, which could be used for many things - like driving, cooking, powering a generator, heating a house. Even though heat and sound are forms of energy, they are not very useful; when you turn the furnace down at night, your house "loses" all the heat from the day. We know that it isn't really gone, but there is not an easy way to recover that energy. In this unit, we will talk about two types of energy - kinetic (motion) and potential (gravitational). The sum of the potential energy and the kinetic energy at all points in a closed system is a constant. That is, PE + KE = constant at all points. KE = ½mv² and PE = mgh ||  || Take a roller coaster as an example of energy conservation in a closed system 250 kg Cart starts at the top (20 m above ground level) with a speed of 4 m/s. Use energy conservation to find the speed at the bottom of the first hill (h= 0), halfway up the next hill (h = 10m) and at the top of the first hill (h = 20 m). Answers are 20.2 m/s, 14.6 m/s and 4 m/s and we can demonstrate that the answers are independent of the mass of the cart. Since there is no friction in a closed system, it is like dropping a marble and a rock from the same height; even though they have different masses, they accelerate at the same rate and hit the ground at the same time) - refer to Neil Armstrong dropping a feather and a hammer on the moon [|feather] || || 1. Work W = F * D, measured in Newton-metres or Joules (equivalent), force and distance must be in the same direction  Work = force * distance (but the force needs to have a component in the direction of motion)  Work done = energy used (in a closed or ideal situation)
 * Dec 21 || ...end of the world day...
 * Jan 8 || Work, Power and Energy

2. Energy - Work equivalence - in ideal situations (no loss of energy, no friction, etc) the energy used and the work done are EQUAL *problems where objects are being moved vertically require you to account for the force of gravity (Fg = 9.8*mass). We could say that we need 0.01 Newtons of force upward to move the object, but in reality we don't even need 0.01 additional Newtons of force. So our calculation allows for upward F = Fg. || Practice problems from handout (above) 151 # 2,3,4 160 # 1,2 163 # 1-4 170 # 1a,b || Power = the rate of doing work. How quickly we get work done. Still dealing with the physics definition of work. Power is measured in watts, but we often use a larger unit - kilowatts. 4. Efficiency - ratio of the output work to the input work (or energy) for some system. In some cases, like energy conservation problems, we assume that systems are 100% efficient. however, we know that there is no such thing as a free lunch (2nd law of thermodynamics, in case you are interested). So we calculate efficiency in one of the following ways: Efficiency = gain in PE / work done = energy gained / energy used = output energy / input energy In its simplest form, Efficiency = what we get / what it costs || p 153 # 1-6 p 170 # 1,2 || Review of Work, Power, Energy, and Efficiency calculations - from homework. || p 168 # 1-3 p 191 # 16-30 || Lab on Thurs/Fri - efficiency and energy conservation Take up problems from 191 - only half of you finished the work. Come on! New problems on work, power, and energy || p 191 # 31,35,39,42,46 ||  || our data: hanging mass (kg): 0.15 0.25 0.30 0.40 0.45 0.60 max speed (m/sec): 0.88 0.99 1.20 1.38 1.45 1.71 (from ticker tape) max speed (m/sec): 0.82 1.02 1.18 1.31 1.47 1.71 (from photogate timer) What is the equation that best fits the data? The fastest way to get an equation is to use the regression tools at Xuru.org Time to start serious work on your presentation topics - presented during the last week of Feb Test on Energy, work, power, conservation - next Thursday - here is a review || Review the calculations from this unit. to be handed in by Friday. Here are to check your work a) 89200 J b) 18.9 m/s
 * Jan 10 || 3. Power P = W / t, measured in watts (Joules/sec), the rate of using energy (or of doing work)
 * Jan 11 || Presentation update - we won't worry about them until second semester starts; however, you should have a topic and a few resources already. You also need to decide if you want to do your project in a group of two or by yourself.
 * Jan 15 || Presentation update - you should have a topic when we return.
 * Jan 29 || Review of energy, conservation, graph and equation from lab
 * Jan 29 || Review of energy, conservation, graph and equation from lab
 * 1) 6 is incorrect - first two answers:

|| Any questions about the quiz - due tomorrow, but not later than Monday Presentation discussion - handout Calculations - energy conservation vs kinematics - both should give the same answer. ex: drop a ball from a height of 25 m; how fast is the ball going just as it hits the ground? ||
 * Jan 31 || Hand in graph plus work plus two equations for the conservation of energy lab.

finish quiz for next class finish last page of energy conservation problems || - total initial energy for roller coaster; includes both KE and PE of roller coaster - speed of object being raised by 500 watt motor; this is not an energy conservation problem. Sample problems for rest of the period ||  || (T/F, definitions, short answer) ||  || Half class - work period for presentation ||  || hand in a sheet of paper that lists your topic, the main point or question of your project, and between 4 and 8 key points or things to investigate. You should be able to complete this for both a research and a building project. ||  || Begin with discussion of earthquakes - location, specific cause, damage - this brings us into a more general discussion of plate tectonics, the Earth's geologic history, and the processes of science. Wave terminology - frequency, period, wavelength, crest, trough, amplitude 3 types of waves - transverse, longitudinal, torsional - distinguished by the vibration orientation (across, along, or around the "rest axis") Calculations of wave speed, frequency, wavelength and period Problems on waves - speed, frequency, period, wavelength ||
 * Feb 1 || First work period for presentation topic - library is reserved for our class today ||  ||
 * Feb 5 || Hand back quizzes - few problems on:
 * Feb 7 || Test on Work, Power and Energy - whole class - half is problems, half is concepts
 * Feb 8 || Half class - introduction to new unit - sound and waves
 * Snow Day || You should be working on your presentation topics. Tomorrow, by the end of class, you will
 * Feb 12 || Begin new unit on sound and waves

p 275 # 1-4

p 282 # 1-6 p 305 # 8-11 || Superposition of waves = interference - waves that meet pass through each other (they are just energy), but at the point of maximum overlap, the waves build each other up or cancel each other out temporarily. We use geometric addition of waves to find the shape of the wave at maximum overlap. What happens when two waves meet? -they pass through eachother, since waves are just energy being transferred from place to place -they interfere constructively or destructively ONLY when they occupy the same space Demo of wave superposition - check out [|transverse wave applet] Review of wave addition - based on homework problems from p 305 This is an example of Interference, the first of four wave properties we will study. The other three are reflection, refraction and diffraction. || P 305 # 14-16, 20, 22, 23, 26, 28, 31, 32 || to go on Tuesday, but if there are no takers, I will draw names from a hat for the first three days. ||  || 2 presentations per class; additional time will be spend on our sound and waves unit. Review the rubric that will be used to assess your presentation and paper/invention today's work - homework problems on wave superposition Also introduction to seismology - how to determine the location (epicentre) of an earthquake? || draw your final circles with a compass Wave superposition p 305 # 33,34,37 || or print a copy of your report and presentation for the teacher || - review of previous work with waves - speed of sound calculations - an interactive earthquake simulation Next week we will take up this work, finish our discussion of resonance and begin the application of waves to music || - [|online] remember to enter the class code so that I can check your work: 2108567
 * Feb 19 || Review of wave speed, frequency, period and wavelength: calculations
 * Feb 21 || final work period for presentations which start next Tuesday. I will ask for two groups to volunteer
 * Feb 22 || Draw for presentation dates - start with students who have conflicts for the second week
 * Feb 26 || Presentations - Nathan/Matt, Bernie, Phil || Make sure that you share, email,
 * Feb 28 || Presentations - Teri/Rebecca, Lizzy, Rachel ||  ||
 * Mar 1 || Presentations - Heather, Brittany, Carly ||  ||
 * Mar 5 || Presentations - Sung, Fansong, Nathan ||  ||
 * Mar 7 || Presentations - Kurtis, Mark, Josh ||  ||
 * || **Spring Break** ||  ||
 * Mar 19 || Presentations - Josh, Caleb, Joe ||  ||
 * Mar 20 & 21 || Mr Guetter is gone to a robotics competition at Waterloo today. You will do work on a number of items:

|| 1. two pendulums of equal length; start one swinging and it causes the other one to swing - only if they are the same length. Why is this? Can you explain this in terms of your previous work on resonance? 2. tuning fork - strike it against your palm and slowly rotate the tuning fork near your ear. - why does the sound get louder and softer? Can you explain this in terms of interference? What if you strike the tuning fork and hold it against your table? Why does the sound get louder? - can you explain what is happening in terms of conservation of energy? 3. slinky time - practice sending a compressional pulse and a transverse pulse from one side - can you make it return? What happens to the transverse wave when it reflects? - if you gently shake the slinky, you should be able to see distinct parts of the wave that are always moving and parts that are not moving. the not-moving spots are called NODES and you will try to adjust the rate of vibration so that you see one, two, three, or more nodes. How many did you get? ||  || - video clip from Big Bang Theory - Sheldon and the costume party. Calculation of apparent frequency: F2 = F1 [ v / (v ± s)] where F1 is the original frequency, v is the speed of sound, and s is the speed of the source. We can determine the + or - intuitively OR we can memorize that - means coming toward and + means going away. Homework problems from handout || p 366 # 58-60 finish algebraic problems handout || produce such loud sounds? We used a demonstration with tuning forks, a container of water, and different lengths of hard plastic tubing to learn about resonance. Although every textbook uses transverse waves to teach about standing waves in air columns, sound travels through air as a compressional wave. This means that rather than crests and troughs, there are regions of higher and lower air pressure. And the length of the air column determines whether or not there will be resonance for a specific frequency. For closed (at one end) air columns, there is resonance at 1/4 wavelength, 3/4, 5/4, etc. And for open (at both ends) air columns, there is resonance at 1/2 wavelength, 1, 3/2, etc. And we did calculations to show that, despite the difficulty in representing the standing wave clearly, resonance really does occur at very specific lengths for both open and closed columns. The two links to the right are the best examples that I could find on air columns and resonance. || [|visual explanation of air column resonance]
 * Mar 26 || Demonstrations of resonance today:
 * Apr 2 || Doppler effect - the apparent change in frequency of a wave due to the motion of the source or receiver
 * Apr 4 || Tuning forks and resonance in air columns. Why do organ pipes and other wind instruments

[|standing wave demo] || Watched video (see Ap 4) and went through slides on same topic. Resonance in air columns has more to do with pressure differences in compressional waves than with sine or cosine transverse waves. Problem solving with open and closed air columns ||
 * Apr 5 || Review of resonance in open and closed air columns

p 366 # 47-57 || 1. change in length of string 2. change in tension of string 3. change in diameter of string 4. change in density (material) of string You should be able to calculate the change in frequency of a string due to one or more changes Demo time - use the tuning forks, water-filled graduated cylinders, and tubes to experiment with resonance in closed tubes. || P 366 # 35-43 || Sound intensity, range of hearing, how the ear works, hearing problems Animation of how the ear works - [] Handout - physics of hearing - be able to explain the changes in energy at different points [] Medical technology - Vertigo - problems in the Loss of hearing range as you get older - grandparents. || For the test next week, you should be able to explain how the ear converts sound waves into energy that your brain can process. As well as one or more problems
 * Apr 9 || Calculations of frequency change with strings - four factors - see ppt from Apr 5
 * Apr 16 || Human Ear and Hearing

|| Listing of major concepts for the unit test: 1. wave fundamentals - types, terminology; frequency, period, wavelength, and speed calculations; - interference of waves - constructive and destructive - doppler effect calculations 2. applications of waves - earthquakes (p&s waves, triangulation, travel time); - resonance (examples, factors that contribute to resonance) - sound (open and closed tubes, strings) - hearing and ear disorders (explain the energy transformations that take place; explain at least one medical disorder related to the ear)
 * Apr 18 || Review for test - Tuesday


 * Four variations on a doppler effect problem **

1. car horn has freq of 350 hz, air temp is 20 degrees, car speed is 20 m/s toward you, find the apparent freq. f = 371 hz 2. freq of horn is 350 hz, the apparent freq is 420 hz, air temp is 0 degrees, find the car's speed. v = 55.3 m/s 3. car speed is 100 km/hr away from you, air temp is 10 degrees, the apparent freq is 320 hz, what is the actual freq? f = 346 hz 4. find the air temp if the actual freq is 500 hz, the apparent freq is 460 hz and the car's speed is 30 m/s. T = 22 degrees || Assign 4 doppler effect problems; collect quizzes - return Friday || 1. describe the main parts of an atom in terms of location, size, and charge 2. describe the two traditional models of the atom: plum pudding and planetary; are these models accurate? 3. describe the relation between the number of electrons in the outermost orbital of an atom and that atom's location on the periodic table 4. assuming you have heard of Rutherford's gold scattering experiment, explain the significance of the result || on moving charges and energy calculations p. 518 #2, 4, 5 p. 522 #1, 2, 5, 6 p. 530 # 7,8,9,11,13,15 || Introduction to Kirchoff's laws for current and voltage in a circuit: First need to agree on what a series, parallel, and mixed circuits are. And we need to understand current flow (+) vs electron flow (-) - current is equal at all points in a series circuit - current into a branch is equal to the current out of a branch; current in each branch is split, sometimes equally - the sum of voltage (potential difference) drops in any path is equal to the voltage of the battery - voltage drop in any path of a parallel branch is equal || handout on || Very few circuits are entirely series or parallel; most are a combination of the two. In a series circuit, every electron goes through the same path and through every load In a parallel circuit, electrons (and current) are divided among the different paths available; more electrons take the "path of least resistance" Voltage rules: sum of voltage increases (battery) equals the sum of voltage drops in any complete path; every electron in a circuit loses the same amount of energy, regardless of the path taken; the voltage drop in any section of a parallel branch is equal. Current rules: remember that current flows from + to -, while electrons flow from - to +. We use electron flow in this class. Kirchoff's laws for current tell us that: the current at any point in a series circuit is equal; the current into a junction or split is equal to the current out of a junction; the series current is split when it enters a parallel branch, sometimes equally. ||  || Introduction to Ohm's law, which allows us to calculate the current, voltage, and resistance both in an entire circuit and in an individual device. 1. for a single device, if we know two of resistance, voltage and current, we can calculate the third. 2. for an entire circuit, things are a bit trickier because we need to find the total (called Effective) resistance: - for a series circuit, the effective resistance is the sum of all the individual resistances - for a parallel circuit, the effective resistance is NOT the sum of the individual resistances. It can easily be shown that as you add more branches to a circuit, the resistance goes down. Think of the truck analogy: as you add more roads, even if the roads have toll booths, potholes, or protestors, more trucks get through than on a single road with only one of those obstacles. || P 538 # 1-4 p 551 # 1-5 || The calculation is 1/Re = 1/R1 + 1/R2 +1/R3 ... Think of it this way. If a circuit has a resistance of 10 ohms and we add more pathways, more electrons will get through (per second). That means the resistance has gone down - even if the new branches have higher resistances. We need this information to solve P 551 # 5, since we can only calculate the current in the circuit if we know the total resistance. Another way to deal with parallel resistors: the ratio of the resistances is the opposite of the ratio of the currents allowed through. For example, with parallel branches of 10 ohms and 30 ohms, the ratio is 1:3. this means that 3 times as many electrons pass through the 10 ohm resistor. We can think of this as 3/4 going through the 10 ohm and 1/4 going through the 30 ohm. Cool, huh? || P 564 # 21 a-e || In series - the total resistance is the sum of the individual resistances - Re = R1 + R2 + R3 ... In parallel - the total resistance goes down as more branches are added, even if each one has resistance. 1/Re = 1/R1 + 1/R2 + 1/R3 ...
 * April 19 || Review of sound and waves unit - here is a quiz for the second half of the unit - handed out last class ||  ||
 * April 23 || Test on waves and sound - whole class ||  ||
 * April 25 || Beginning of Last Unit - Electricity and Magnetism
 * Based on what you have learned about atomic structure in chemistry class **
 * April 26 || Dump truck analogy for electricity - number of roadways, size of load, speed of truck (all three relate to electricity concepts of voltage, current and resistance)
 * April 30 || Most of the class is gone today, so we reviewed the calculations for kirchoff's laws.
 * May 2 || Review of Kirchoff's laws for series and parallel circuits. take up first set of calculations.
 * May 3 || So, is there a way to calculate the effective resistance of a parallel branch in a circuit? And by effective resistance, we mean "what single resistor could replace that parallel branch and not affect the circuit?"
 * May 7 || Resistance in series and parallel - how to determine the total (effective) resistance. [[file:guetter/resistance.pdf|resistance.pdf]]

Review of rules for current and voltage in circuits - questions from handouts. Introduction to Power Two new concepts - power and cost of energy 1. Power = rate of using electricity = V²/R = I²R = VI answer is in watts It is more useful to use kilowatts, since watts are a very small unit; in fact, household energy consumption is measured in kilowatt-hours, that is, 1000 watts used for one hour. The cost per kw-hr is between 6 and 10 cents in North America. 2. Cost of Electricity = # of kw used * # of hours * cost per unit || 2 problems on board: power used in circuit cost of using hair dryer P 564 # 16, 17, 26 || We watched the first 13 minutes of the video in class. Come prepared with additional info on Friday. Questions to answer: 1. explain how the body uses electricity to function 2. explain how a taser disrupts the electrical system in the body 3. explain/list any significant side effects of taser use 4. in your opinion, are tasers safe? Here's [|another report] from CTV News about at 11 year old who was tasered by police And here is a [|60 Minutes report] on taser safety - CBS ||  || p 538 # 1-4, 551 # 1-5, 564 # 21 a-e, 564 # 16, 17, 26 New work for today is to do energy, resistance, power and cost problems: p 541 # 1-5, 545 # 1,2, 554 # 1-4, 556 # 1-4 You also need to finish your half-page answer to the four questions from yesterday's lesson on Tasers. This will be on the next test, so you need to know some specific details about tasers and their effect on the human body. ||  || Set date for next test - Tuesday, May 28 - last test of the course. Discussion of energy consumption, usage rates in Ontario, and circuit breakers in household circuits. Hand out quiz - this is all review, so find out where your gaps are. ||
 * May 9 || Resistance of the human body - application to taser use, specifically to the Robert Dziekanski death. The electrical nature of the human body and the use of high voltage to disrupt the natural communication system within the body. [|Video] from CBC and written supplement [[file:guetter/taserCBC.pdf|taserCBC.pdf]]
 * May 10 || Mr Guetter is gone today. You need to finish the assigned problems from:
 * May 14 || Take up questions from previous class

|| 1.A current flowing through a wire induces a magnetic field. In elementary school you created an electromagnet by wrapping wire around a nail or bolt and then connecting the ends of the wire to a battery. Although the nail or bolt makes the electromagnet stronger, the magnetic field is a result of current flowing through the wire coils. 2.A wire that passes through a magnetic field induces a current in the wire. This is the key idea for our discussion on electricity generation. Although modern technologies (solar and wind) don't involve the motion of a turbine or generator, most of the large-scale electricity generating plants use steam or water to spin a turbine. Your class presentation will explain how energy is converted and how electricity is produced. ||  || Application - building a small electric motor using a battery, a magnet, paper clips, and wire. Here is the website that I refer to [|http://scitoys.com/scitoys/scitoys/electro/electro.html#motor] Don't worry if your motor does not work on the first day. We will make adjustments to the design on the second day. ||  || Second day for building electric motor. Those who were not able to get their motor working properly, take a look at the one that is working well. The goal for the day is to have one group's motor working with an electromagnet, rather than with a bar magnet. ||  ||
 * May 16 || work period for electricity generation project - in pairs, present one method of electricity generation from the list given in class. Your presentation should thoroughly answer the four questions || [[file:electricquiz.doc|electricity quiz2]] ||
 * May 17 || Two key ideas in electromagnetism:
 * May 21 || Review of two rules of electromagnetism.
 * May 23 || Review for electricity test next Tuesday - hand back quizzes
 * May 24 || Project Day - you should finish your handout for the electricity presentation, study for the test, or begin organizing your notes for the final exam. I will give you a formula sheet early next week. ||  ||
 * May 28 || Test on electricity unit - whole class ||  ||
 * May 30 || Review for final exam - day 1 - handout of sample problems, of general topics to study, and a formula sheet. ||  ||
 * May 31 || Presentations for electricity generation - each group requires a one-page handout that I can photocopy before class. ||  ||
 * June 4 || Presentations for electricity generation - each group requires a one-page handout that I can photocopy before class ||  ||
 * June 6 || Review for final exam - day 2 ||  ||
 * June 7 || Review for final exam - day 3 ||  ||
 * June 11 || Last day of class - review questions, class party || [[file:ExamPracticeProbs.pdf|Solutions to exam review]] problems - # 1b is 7.5 seconds ||