Presentation on theme: "Relative Motion 1 TELESCOPES GOOOOOOOO!. Relative Motion 2 Make cut out bus or train with the windows cut out, 2 or 3 cut out people, a beautiful background."— Presentation transcript:
Relative Motion 1 TELESCOPES GOOOOOOOO!
Relative Motion 2 Make cut out bus or train with the windows cut out, 2 or 3 cut out people, a beautiful background (forest, city, etc), and your phone. 1.Place your cut out bus on the background and place your people on the bus. Move the people back and forth at the same speed within the bus. Keep the viewing frame of your phone locked on (moving with) the cut out people. According to what you see in your viewing frame, are the people moving? 2.Move the people and the bus back and forth while keeping your viewing screen locked on the bus and having the bus fill up your viewing screen. How are things moving? 3.Now keep your viewing frame locked on the background and slowly zoom out. How are things moving?
A blue car moves along a street with two passengers. One sits in the front passenger seat of the car and the other passenger sits in the back seat. A red car moves in the same direction and is passing the blue car. A green car moving faster than the blue car, is directly behind the blue car. There is a sidewalk along the road the cars are traveling and a pedestrian is standing on the sidewalk. Relative Motion 3 Describe the movement of the front passenger in the blue car as seen by each of the following observers: 1. The person sitting in the backseat of the blue car. 2. The pedestrian standing on the sidewalk as the blue car passes. 3. The driver of the red car moving in the same direction and passing the blue car. 4. A passenger in the green car.
A blue car moves along a street with two passengers. One sits in the front passenger seat of the car and the other passenger sits in the back seat. A red car moves in the same direction and is passing the blue car. A green car moving faster than the blue car, is directly behind the blue car. There is a sidewalk along the road the cars are traveling and a pedestrian is standing on the sidewalk. Relative Motion 4 1. Imagine you are the backseat passenger in the blue car, how would you observe the other four observers? Explain. 2. Imagine you are the pedestrian in the street, how would you observe the other four observers? Explain. 3. Based on your answers above, explain what it means when someone says an object is “moving”. 4. Consider the phrase “motion is relative”. Use your idea of what it means to move to explain the meaning of this statement.
Tom is on a train moving at 10m/s when he drops his phone from his hand to the floor of the train 1.5m away. If Jon is standing on the ground outside the train 7m from Tom when he begins to drop his phone, how far away from Jon will the phone land? Relative Motion 5
Erin, Chris, and Dhruv are on their way to a vacation. They are racing to the train from three separate locations Alex makes it to the train on time and sits in the back of the train. Dhruv barely makes it there on time and the train pulls out of the station at -20m/s. Dhruv walks to the back of the train to meet Erin at 3m/s. Chris does not make it to the train. He stands and watches as the train pulls away. What are the velocities of the following? a. Erin relative to Chris b. Dhruv relative to Chris c. Dhruv relative to Erin d. Chris relative to Erin e. Erin relative to Dhruv f. Chris relative to Dhruv Relative Motion 6
Erin, Chris, and Dhruv are on their way to a vacation. They are racing to the train from three separate locations Alex makes it to the train on time and sits in the back of the train. Dhruv barely makes it there on time and the train pulls out of the station at -20m/s. Dhruv walks to the back of the train to meet Erin at 3m/s. Chris does not make it to the train. He stands and watches as the train pulls away. What are the velocities of the following? a. Erin relative to Chris b. Dhruv relative to Chris c. Dhruv relative to Erin d. Chris relative to Erin e. Erin relative to Dhruv f. Chris relative to Dhruv Relative Motion 7
Velocity 8 A toy car moves 2m every 2s for 10s. What kind of a representation is this? Create as many representations of this as possible. Verbal Picture Index Table Function/Equation Plot Graph Motion Diagram
Smashy Smashy Car Crashy Where will 2 cars collide? Velocity 9
Curiosity Observe Data then Hypothesize from Data Patterns Observation Experiement Method Materials Timer Meter Sticks Sand Bags Blue & Red Car Procedure Error/Uncertainty Results Data Reason a Hypothesis from Patterns in Data Velocity 10
Represent Car Motion Hypothesis Using all of the Following Representations… Verbal Picture Index Table Function/Equation Plot Graph Motion Diagram Some of these representations overlap (e.g. you need an index and equations in your motion diagram) Velocity 11
Skepticism Predict to Test your Hypothesis Predict the outcome of a Testing Experiment assuming your Hypothesis is correct. Perform the Testing Experiment then compare the actual outcome to your prediction. Your test is an experiment and must include… Testing Experiement Predict Method Materials Procedure Error/Uncertainty Results Data Compare Predicted to Actual Outcome, Revise if Necessary Velocity 12
Represent Car Motion Prediction Using all of the Following Representations… Verbal Picture Index Table Function/Equation Plot Graph Motion Diagram Some of these representations overlap (e.g. you need an index and equations in your motion diagram) Velocity 13
Four friends represented the motion of the same car in different ways. Which would best represent the motion of the car as a function of time? Draw the one you think is best and label why. Velocity 14
Mayes and Patel are at the boardwalk. They are riding bumper cars and heading straight towards each other. If they start 10 m apart, M is going 1m/s, and P is going 2 m/s, where will they meet? Answer with a motion diagram and plot graph. Velocity 15
Represent this data with motion diagrams, graphs, and equations. Predict where they will meet. How did you predict? Position (x)Time (t) 1m0s 2.5m1s 4m2s 5.5m3s Position (x)Time (t) 10m0s 8m1s 6m2s 4m3s Shiv Megha Velocity 16
Kevin sees a spider crawl up Nishi’s leg and measures position each second. Nishi measures her hand’s position each second to squash the bug. When and where does she squash the bug? Use MD’s, and plots. What can you say about the motion of Nishi’s hand? 0s Acceleration 17
Acceleration 18 Hypothesize the motion of a ball if you set it in motion then let it roll to a stop. Materials: Meter sticks, balls, sand bags, books, timers
Nainil measured a bug scampering away. Create a motion diagram. Plot these points on a position vs. time graph. Find the change in velocity between each dot from the the 1 st dot to the 11 th. 0s Δ t = 1s Acceleration 19
Acceleration 20 Cheryl and Wendy are exercising in Roosevelt Park. When you start observing them, Wendy is 50 meters ahead of Cheryl. Wendy is jogging at a speed of 5 mph and Cheryl is running at a speed of 7 mph in the same direction. Dan is riding a bike at 21 mph in the opposite direction of Wendy ’ s velocity. He is 12 meters ahead of Wendy in the opposite direction of Cheryl ’ s start point when you start observing them. How far will Dan be from Cheryl and Wendy when Cheryl catches up to Wendy? 638m
We have learned that V = Δx/Δt Using this, what is acceleration? Use words and equations for your answer. Acceleration 21
Tim rolled me down a hill. Plot-graph this data of my position at a clockreading. What is each ΔV and acceleration? Plot velocity versus time. PositionTime 1m1s 4m2s 9m3s 16m4s 25m5s 36m6s 49m7s Acceleration 22
Dennis throws a tennis ball away from Earth with an initial velocity of 100 m/s up. Make a position vs. time graph and V vs. t graph. What is the acceleration? How high does it go (distance)? How far away is it from where it started (displacement)? Time (s)Position (m) Acceleration 23
An object has an initial vertical velocity of V i = 10m/s. Create a problem with rubric which uses this as the answer. Acceleration 24
How do we calculate acceleration? How could we find V f from this if we know all other physical quantities? Kinematic Equations 25
Kinematic Equations 26
Create a mathematical procedure for finding the area under the graph. VfVf ViVi Kinematic Equations 27
By breaking the area under the curve into a rectangle (area=v i t) and triangle (area=½(v f – v i )t) then adding them together we get Kinematic Equations 28
Derive the following kinematic equations below from three you have derived. Kinematic Equations 29
Substitute to get into Kinematic Equations 30
Multiply to get by Kinematic Equations 31
Kinematic Equations 32 Draw a motion diagram for an apple falling from rest for 4 seconds. What will the V f of the apple be?
Kinematic Equations 33 Make a story for each graph both verbally and mathematically.
Kinematic Equations 34 Create a problem with a rubric whose answer is a = -4.6m/s 2.
Gokul ‘Flash’ Murugesan’s motion is described in equations below. Use as many other representations as possible to describe this motion.
2D Kinematic Equations 36 Jess and Matt are walking down a hallway. Matt is carrying a box of Mentos™ and Jess is carrying a crate of Coke™. Will they be covered in explosive grossness?
2D Kinematic Equations 37 An airplane accelerates at 2m/s 2 due East from a speed of 700m/s for 50s. How fast will the plane be going if there is also a 100m/s wind blowing at 33 o North of East?
Cheryl pegs Mr. Mayes with a snowball. The snowball leaves Cheryl’s hand with a velocity of 10 m/s at an angle of 30 o away from the ground (Earth). Projectiles and 2D Motion 38
The First Half of the Trajectory Y or Vertical Dimension After the balloon leaves the launcher, it travels upward in the path of a parabolic arc until gravity decelerates it’s vertical, upward motion to a stop. Projectiles and 2D Motion 39
Second Half of the Trajectory Y or Vertical Dimension Gravity then accelerates the projectile downward from the top of this arc. Projectiles and 2D Motion 40
Hang Time (Δt) Using the kinematic equations we need to calculate how much time it takes for the Y velocity from the sling to decelerate to zero at the top of the first half of the projectile’s trajectory. This gives us half of our “hang time” (Δt 1/2 ) or half the time the projectile spends in the air. Multiply by 2 to get the total hang time and use the kinematic equations to find the distance the projectile travels in it’s trajectory. Projectiles and 2D Motion 41
The Whole Trajectory X or Horizontal Dimension With no forces acting in the horizontal or X dimension after the initial projection, what does the X velocity do throughout flight? Projectiles and 2D Motion 42
The Whole Trajectory X or Horizontal Dimension If we use trigonometry on the initial velocity out of the sling, we get the constant velocity of the balloon in the X direction throughout flight. We also have the hang time. We have a rate (V) and a time interval (Δt), so we are able to get the total displacement the balloon travels from d = VΔt Projectiles and 2D Motion 43
Cheryl pegs Mr. Mayes with a snowball. The snowball leaves Cheryl’s hand with a velocity of 10 m/s at an angle of 30 o away from the ground (Earth). How far away from Cheryl is Mr. Mayes standing? Patel Pegs Mayes Projectiles and 2D Motion 44
Projectile Physics Hypothesize Design an experiment to hypothesize what the initial velocity of a marble being shot out of your launcher is. ***!!!Reminder!!!*** Experiments need methods, data, assumptions and error/uncertainty. Analysis of the data is looking for patterns and your conclusion is your hypothesis from these patterns. Projectiles and 2D Motion 45
Projectile Physics Predict Now we test our hypothesis by predicting how far our launcher will launch if firing at a 30 o angle. Projectiles and 2D Motion 46
Daredevil Canyon Jump Aditi ‘The Awesomizer’ tries to jump a canyon of width 80m. To do so, she drives her motorcycle up a ramp. The ramp is at an angle of 17.5 degrees up from the ground. What minimum V i is necessary to successfully jump the canyon? Express your answer with JUST variables first, then put quantities in. Not to be outdone, Gunica ‘The Brawler’ Bhatia attempts to jump an even larger part of the canyon. She measures the canyon and calculates that her initial speed must be 26.7 m/s at an angle of 17.5 degrees to just barely clear the larger part of the canyon. What is the width of the canyon here? Express your answer with JUST variables first, then put quantities in. Projectiles and 2D Motion 47
Let’s make our own projectile problems. Your group will have to create three problems. These problems have to solve for: 1. Θ 2. ΔX 3. V i Your problems must have answers and a rubric. Projectiles and 2D Motion 48
Lets consider a ball being launched across a flat field where the initial and final heights of the ball are the same. Derive an expression for the horizontal distance travelled solely in terms of the initial velocity, acceleration due to gravity, and the angle at which it is fired. Projectiles and 2D Motion: Range Equation 49 ***Hints!!!*** 1.How could we make our reference frame as easy as possible for ourselves? 2.What kinematics equation could we use which requires the least assumptions and is the most comprehensive? 3.How do we link the horizontal and vertical components? 4.How could we simplify?
What similar action is involved in all of the following activities? You pedal a bicycle to start moving then apply the brakes to make it stop moving. You hit the accelerator (gas pedal) to make a car speed up after the light turns green, then you hit the brakes to stop for the next red light. A spring pushes a marble to accelerate it out of your launcher. You push a baseball to speed it up for a throw. A friend then pushes on the ball after it enters her glove to slow it down and catch it. Newton’s 1 st and 2 nd Law 50
To hypothesize anything you must find patterns in data. To obtain the data you must conduct observation experiments Like all experiments, this must have methods, analysis of assumptions, and analysis of error/uncertainty. Hypothesis… Must be based on the pattern you devise from all data from all observation experiments. Must use multiple representations and usually as variables in an equation (proportional relationship between physical quantities). Science Method Recap 51
Hypothesize how pushes and pulls change motion of different masses. Materials (every single material MUST be used… this means you should design multiple experiments) Mass scale Your muscles (you lift things up and put them down… grarghhh!!!!!) Big ball (bowling/medicine) *1kg=2.2046lbs on Earth* Medium ball (tennis/baseball) Small ball (marble) Stopwatch Meter stick Newton’s 1 st and 2 nd Law 52
Make a diagram with force vectors for a box sitting stationary on the ground. Force Diagrams 53
Make a force diagram for a box being pushed on a rough surface but remaining stationary. Force Diagrams 54
Make a diagram for a box being pushed along a rough floor at a constant velocity. Force Diagrams 55
Draw motion and force diagrams for the following: -You are driving in the school parking lot when a man in a gorilla suit sprints toward your car. You hit the gas to get away from this weirdo. -A very large water balloon is projected vertically near the school on a day when the air is thick but there is no wind. -A raw egg is projected across the parking lot at Mayes’ car. Force Diagrams 56
A rectangular sheet of material has a width of 3m and a length of 4m and is held stationary to look taller rather than wider. A 3N pull is exerted in the upper left corner to the left and a 4N pull is exerted in the lower right corner in the downward direction. What is the magnitude of the force exerted from the person in the upper right corner at what angle relative to the top side of the sheet? Explain all answers, justify assumptions, and use multiple representations. Force Diagrams 57
Newton’s 3 rd Law 58 Hypothesize how two things push or pull on each other. Materials: 2 bathroom scales 2 spring scales 2 scooters
Jackie exerts a 9.8 N force upward on a 1 kg snowball on Earth. Draw this situation focusing on the snowball. Newton’s 3 rd Law 59
Jackie exerts a 9.8 N force upward on a 1 kg snowball on Earth. Draw this situation focusing on Jackie’s hand. Newton’s 3 rd Law 60
Make a chart of representations for Newton’s Laws which includes Math, Words, Diagram, and Example. Newton’s Laws 61
Make a force diagram for 3 stationary, stacked boxes. The most massive box is on the bottom and the least is on the top. Use a separate diagram for each box as the system and one for all three as the system. Force Diagram Problem 62
Make a diagram for 2 boxes (top 3kg, bottom 5 kg) stacked vertically and being pushed horizontally along a rough floor at a constant velocity. Force Diagram Problem 63
A 2000 kg car sits on a 60 o hill in San Francisco. What is F staticfriction on car ? Force Diagram Problem 64
Three boxes (top 1kg, middle 3kg, bottom 5 kg) are stacked vertically and being accelerated horizontally along the floor at 5 m/s 2. The force of kinetic friction exerted from the ground on the bottom box is 500N. What are all of the forces exerted on each of these boxes as shown by a diagram? Force Diagram Problem 65
Two masses are vertically hanging on either side of a pulley (this is called an Atwood machine). One of the objects has three kilograms of mass. What is the mass of the other object if it is stationary? What is the mass of the other object if it is moving at a constant speed downward? What is the mass of the other object if it is accelerating down at 2m/s 2 ? What is the mass of the other object if it is accelerating up at 2m/s 2 ? Atwood Machine 66
Predict to test Newton’s Laws Materials: phet.colorado.edu ‘Forces and Motion’ Newton’s Laws 67
Hypothesize how friction operates on a subatomic scale. Materials: phet.colorado.edu ‘Friction’ Friction Force 68
Friction Force 69 Hypothesize the relationship between the friction force of the floor on your shoe and the amount of normal force exerted by the floor on your shoe.
Friction Force Problem 70 If a 3500kg object rests on a hill with a 37 o slope and is stationary, what is µ static ?
Friction Force 71 If a 3500kg object slides on a 37 o slope and is µ kinetic = 0.004, describe this object’s motion?
Spring Force 72 Hypothesize the relationship between the force used to stretch a spring and the distance it is stretched.
Spring, Tension, and Friction Force 73
4 kg 12 kg µ kinetic = 0.02 Spring, Tension, and Friction Force 74 a large = ? Assumptions?
Scientific Method for Forces 75 Hypothesize using the following materials: 1.String 2.Pulleys 3.Masses 4.Balloons (Helium and Atmosphere) 5.Springs 6.Measuring Devices
Hypothesize a quantitative model for the force which moves objects in circles. Materials: ball on a string Central Force 76
Meghana spins a ball around her head on a string. The velocity of the ball is 5 m/s, the ball has 1.3 kg of mass, and the radius of the circle she is spinning is 2m. Draw a diagram of this situation with all necessary physical quantities including the central force and acceleration. Then draw this same situation for: 1) Doubled velocity 2) Halved radius 3) A ball 4 times larger ***Make sure to create multiple representations and list assumptions.*** Central Force 78
It takes 34s for Vidya to do a full circle doughnut in a snowy parking lot with his car. The lines in the snow from the car are 10m wide. What is the circular acceleration of car while it is doughnuting. Central Force 79
Mr. Mayes is swinging a bucket of water above his head. The bucket and the water is 10kg. Mayes’ total wingspan is 78 inches and it takes him 2 seconds to spin the bucket. Create force diagrams for the top and the bottom of the motion. Central Force 80
Indiana Jones has a 3kg mass at the end of his 3m long whip to fight the UngaBunga tribe of cannibals. What does he have to do with his whip to stun them with 100 N of force? If he has to stun the tribal chief which takes 9 times the force, what will he have to do? Central Force 81
Hypothesize the relationship between the quantities which determine the gravitational force between two objects. Materials: phet.colorado.edu ‘Gravity Force Lab’ Gravitational Force 82
Gravitational Force 83
Draw a diagram of the force exerted on objects with mass (system masses) by a massive central object (source mass). THEN ERASE THE TEST OR SYSTEM MASSES (not the center source mass) Gravitational Force Field 84
What is the gravitational force between Earth and Sol (the sun)? 3.5 x N Electric Force 85
Make a Venn diagram comparing Motion (Kinematics) and Forces (Dynamics). 1 D Momentum 86
Consider the following: 1.A softball is pitched underhand. 2. The driver of an Abrams tank hits the gas. If they both have the same final velocity and acceleration to get to that final velocity, what is different about these two scenarios? How would the force and motion diagrams for these two compare? How could we account for this? 1 D Momentum 87
You have bowling balls, pool balls, tennis balls, and golf balls. Create experiments to observe what happens during various collisions. Invent a physical quantity to communicate these situations. Keep in mind this physical quantity must combine the factors unique to motion and forces respectively. 1 D Momentum 88
Hypothesize the aspects of this new physical quantity (momentum). Design experiments using: 1. pool ball and a golf ball 2. phet.colorado.edu ‘collision lab’ Make sure to identify the independent, dependent, controlled, and confounding variables. Include assumptions and error. 1 D Momentum 89
Summary of Momentum P=mV units are kg(m/s) Impulse changes momentum J=mΔV=FΔt Momentum can be transferred from one object to another. Momentum is conserved if there is no impulse (outside force exerted in a change in time) exerted on the system ΣP i + J = ΣP f Collisions can be described as inelastic (sticky) or elastic (bouncy) Momentum is described with diagrams, math(s), and bar charts 1 D Momentum 90
Create bar graphs to chronicle the following scenario. You have no money in your pocket, $60 in your ATM account, and a gift card with $20 on it. You withdraw $20 cash from the ATM. Next, you buy a lemons and a pitcher for $10 cash at Jones Grocery. (The initial state for this process is the same as the final state of the previous process.) After returning from the grocery store, you make lemonade and manage to sell enough to make $10. When you are finished selling lemonade, you spend $20 cash to put gas in your car so you can drive to Target. At Target, you purchase the new Super Mario Brothers game for Wii for $50. You empty out your gift card and use your ATM card to pay for the rest. Conservation of Momentum Bar Graphs 91
A 70.0 kg man and his 40.0 kg daughter on skates stand stationary together on a frozen lake. If they push apart and the father has a velocity of 0.50 m/s eastward, what is the velocity of the daughter? (neglect friction) Include a momentum bar graph and other necessary representations. Momentum 92
The velocity of a 6.00 x 10 2 kg elephant is changed from 10.0 m/s to 44.0 m/s in 68.0 s by a constant force from a truck which is shipping it. What is the impulse on, force exerted on, and acceleration of this object? Do this in as many ways as you can think of. Momentum 93
5 kg 3 kg 2m/s 5 kg 3 kg 0.5m/s ?m/s After Before 1.Analyze this scenario in terms of momentum. 2.Analyze this scenario in terms of forces and motion. Momentum 94
Aditi and Cheryl are competing over who can make a ball stay airborne for the longest amount of time. The displacement through which Aditi accelerates the ball out of her hand is 0.2m, while Cheryl accelerates the ball out of her hand during the throw in exactly 2s. Aditi throws the ball with an initial speed of 40 m/s and Cheryl throws her ball so the total vertical path covered is 164m. When the balls hit the ground they both have an inelastic collision with the ground and an impulse of 75 kg m/s is exerted on the balls by the ground. Whose ball stays in the air for the longest amount of time? Momentum Problem 95
We created momentum as a replacement for using both motion and forces together… but does momentum always make our physics easier? Does it always work? Create testing experiments to test the hypothesis that momentum P=mV ΣP i + J = ΣP f is a viable physical quantity which makes doing physics easier. You are trying to DISPROVE this. Nothing is proven… ever… nothing… nada… zilch… goose egg. Work 96
Suggested Materials Chalk and brick String with sandbag Wind up Toys Whatever your creative minds can come up with (within the bounds of reason and politeness) Create testing experiments to test the hypothesis that momentum P=mV ΣP i + J = ΣP f is a viable physical quantity which makes doing physics easier. Work 97
Materials: Chalk and massive object For cases wherein momentum is no longer a viable physical quantity to use, invent a new physical quantity to analyze these phenomena. Work 98
What is fundamentally different between the physical quantity you invented and momentum? What about your new physical quantity allows makes it easier to analyze the situations momentum couldn’t? Work 99
A man carries a 5kg bowling ball up a 2m ladder then walks another 5m on the roof while carrying it. How much total work is done on the bowling ball? Make sure to make both a force and motion diagram for each part. Work 100
What is different and similar between the everyday idea of work and how we describe it in physics? Work 101
Hypothesize where work goes when you do work to lift a tennis ball. Derive a mathematical expression for the amount of ‘stored work’ whenever work is done lifting something. Stored Work 102
Hypothesize where work goes when you do work to move an object. Derive a mathematical expression for the amount of ‘stored work’ whenever work is done to move something. Use the equation for work you discovered and kinematic equations. Stored Work 103
Hypothesize where work goes when you do work to stretch a spring. Make a spring force vs. displacement graph. Derive a mathematical expression for the amount of ‘stored work’ whenever work is done stretching a spring. Stored Work 104
Work gets stored as Energy Work done stretching a rubber band or compressing & stretching a spring is stored as elastic potential energy » EPE=0.5kΔx 2 Work done lifting an object such as a ball is stored as gravitational potential energy » GPE=ma g Δx Work done making an object move is stored as kinetic energy » KE=0.5mV 2 Energy 105
You stretch a slingshot 1m which has a spring constant of 1000N/m. You place a 1kg ball in the slingshot. Ignore air resistance. If you release it vertically, how high will it go? What will the final velocity of the ball be? Energy 106
Design a virtual observation experiment to discover an explanation of friction in terms of work and energy. Materials: PHET Friction Friction with Energy 107
Mayes is driving home from a full night of coming up with awesome things to do in class. My car masses 1,633 kg and is moving at 20.0 m/s. There is a red light 40m ahead of me. The coefficient of kinetic friction between the road and my car tires is Will I run the red light or stop in time? Do it with energy, momentum, and forces. You Choose What To Use 108
You stretch a slingshot 1m which has a spring constant of 1000N/m. You place a 1kg ball in the slingshot. Air resistance is 2N for the entire flight. If you release it vertically, how high will it go? What will the final velocity of the ball be? Energy 109
You stretch a slingshot 1m which has a spring constant of 1000N/m. You place a 1kg ball in the slingshot. Air resistance is 2N for the entire flight. Energy 110 Analyze this situation with a bar chart assuming the system is: 1.The ball. 2.The ball and Earth. 3.The ball and the slingshot. 4.The ball, the slingshot, and Earth. 5.The ball, the slingshot, Earth, and the surrounding air.
Design and perform virtual testing experiments to test the following hypotheses separately on Energy Skate Park PHET: Work and Energy is Conserved KE=1/2mV 2 GPE=mgΔx I suggest you turn on and use all tools available to you in the simulation. FRICTION MUST BE ‘ON’ WITH A COEFFICIENT OF FRICTION BETWEEN ‘NONE’ AND ‘LOTS’. Energy 111
Energy 112 Something happened one day and it was described by Matt in the following way. ½ kx 2 + W drag = ½mV 2 + mgy Create a scenario for what this could possibly describe with a diagram, a bar chart, and words.
Hypothesize the maximum velocity of a bouncy toy using only measuring tape. Energy & Momentum 113
Hypothesize the spring constant of your springy toy using only measuring tape and a mass scale. Energy & Momentum 114
Hypothesize the work done in each single wind of a wind-up toy using measuring tape and a spring scale. Energy & Momentum 115
Energy & Momentum Conservation 116 A Newton’s cradle consists of a series of metal spheres hung in a row. One is raised then falls as a pendulum and strikes the row of other spheres. Thus, a sphere at the opposite end bounces up. It is possible for one sphere to fall on one end and have a sphere raise on the other side. Likewise, it is possible for two spheres to fall, strike the row, and two spheres bounce up at the other end. Is it possible for one sphere to strike the end and have two sphere bounce up on the other? Is it possible for two spheres to strike one end and have one bounce up on the other?
Gravitational Potential and Electric Potential Energy 117 Hypothesize how much energy is had by two charges near each other. Hypothesize how much energy is had by two masses near each other. Materials: Your expression for gravitational force, electric force, and mechanical work. Phet – Gravity Force Lab
What is similar and different about these situations? Compare with a Venn diagram. Then, come up with a physical quantity (index) to compare the two scenarios. A flexed muscle quickly pushes a marble with 10N of force over 1m. A light breeze pushes a marble slowly with 10N over 1m. Power 118
What is different and similar between the everyday idea of power and how we describe it in physics? Power 119
Power 120 A 5kg box slides to a halt from 5m/s over a distance of 20m. What is the coefficient of kinetic friction between the ground and the box? How much work is done due to friction on the box? 62.5 J How much power is exerted on the box? m = 5kg V 0 = 5m/s V f = 0m/s ΔX = 20m
You have various ramps with the same height but each have different paths. If we roll marbles down each of these ramps and release them at the same time, predict which ramp will take the least amount of time for the marble to travel from the top to the bottom. Power 121
a) You rescue a 0.05kg bird from the sidewalk and place it back in its nest, 5.2m up in a tree, in 1.0s. b) You lift a 6kg bag of Oreos 3.0m up to your tree house in 6.0s for your slumber party with your friends (you have been saving up for all the Oreos). c) You lift a 10.4kg bag of rice 2.6m to the top of the pantry for your mom in 2.3s. d) Your 70-kg sister twisted her ankle so you lift her from the foyer to the second floor 4.0m straight up in 10.0s. Power 122 You have developed superpowers overnight. You can now stretch your arms to reach ridiculous heights. You decide to become a hero and on your way home from school, you do the following heroic acts. Determine how much power you exert while lifting the following objects. Draw a picture of the initial and final states.
Exercise Power House You’ve got the POWER! Hypothesize the amount of power required to run up a single stair. BE VERY VERY CAREFUL! Power 123
Exercise Power House Now that we know the power delivered by legs while climbing stairs, create a proposal for a Stairmaster which will power all the lights in a house (ignore the kitchen). Many assumptions must be made to do this. Power 124
Simple Machines 125 Bree and Yash are debating the best way to put bowling balls away on the lab table after an experiment. Bree says it is easier to use a ramp to roll the bowling ball back to the lab table she got it from. Yash says it is easier to simply lift the ball and put it on the lab table. Who is right? Design experiments to gather evidence to validate your claim.
Simple Machines 126 Tim claims that he made a machine out of a simple pulley and a string which will reduce the amount of work done to lift a mass to a specific height. Create a testing experiment with a prediction to test this hypothesis.
Simple Machines 127 Do research and design your own simple machine which does something to improve your life!
Misconceptions 128 Misconceptions Motion is absolute. Everyone will agree on the motion of an object. A force is required for motion. Objects eventually stop with no forces exerted on them. Motion is in the direction of the net force. For every action there is an equal and opposite reaction and the sum of the 'actions' is 0. Nothing is conserved if there is impulse/work. A large truck collides with a compact car. The truck exerts a greater force and conveys a greater momentum to the car. A ball is projected up by a spring and there is no air resistance. If the ball is the system no work is done, energy just transfers. Objects move in a circle because of the tangential velocity due to the centripetal force. Semantics of Gravity/Electricity
Concept/Skill from which you must create... Educational Problem with rubric and solution (make it fun or funny). Scientific Experiment to investigate something cool. Engineering Design which will in some way make life easier. Game 129