Monday, March 10, 2014 H Physics

1. Warm Up . Monday, March 10, 2014 H Physics Building to Standard: 2a: Students know how to calculate kinetic energy by using the formula E=1/2 mv2 Objective: SWBAT finish the Kinetic Energy Lab Describe the transfer of energy as the truck goes down the hill. Agenda Warm Up Turn in Last Weeks Homework Finish Kinetic Energy Lab Homework E#5

2. Warm Up A crane lifts up a box 100 m using a 10,000 N force. How much work is done? How much potential energy does the box gain? Tuesday, March 11, 2014 H Physics Standards: Building to Standard: 2a: Students know how to calculate kinetic energy by using the formula E=1/2 mv2 Objective: SWBAT solve conservation of energy problems. Agenda Warm Up Conservation of Energy Practice Homework P.2 E#5 P.4 E#6

3. Wednesday, March 12th, 2014H Physics Standards: Students know how to calculate kinetic energy by using the formula E=1/2 mv2 Objective: SWBAT understand how to measure the kinetic energy of a moving object. Agenda: Warm Up Review HW Motion Lab Warm Up A 2kg ball drops from 10,000 m in the air. What is the ball’s potential and kinetic energy when it is 2000 m in the air? Homework E#6 P.2

4. Warm Up Thursday, March 13, 2014 H Physics Standards: Students know how to calculate kinetic energy by using the formula E=1/2 mv2 Objective: SWBAT understand how to measure the kinetic energy of a moving object. Which person do you think will be moving faster at the bottom of the ramp? Explain why using physics concepts like energy. Agenda Warm Up Review HW Continue Energy of Motion Lab Homework P.4 EH#7 Energy Quiz – Conservation of Energy (like the diving board homework problem)

5. Warm Up Find the kinetic energy of a 0.5 kg marble rolling down a ramp if the marble has a speed of 2.5 m/s at the bottom of the ramp. Friday, March 14, 2014 H Physics Standards: Students know how to calculate kinetic energy by using the formula E=1/2 mv2 Objective: SWBAT score 80% on their quiz Agenda: Warm Up Check HW Conservation of Energy Quiz Homework E#8 Energy Review

6. Symbols, units and equations Study Guide Equations: Energy & Momentum Conservation of Momentum piT=pFT p=mv Impulse=Δp=FΔt Forces Constant Velocity Constant Acceleration ag=-9.8m/s2 The Two equations of Motion for Falling Objects The Two equations of Motion 1. 2.

7. Work Stations • Objective • You will derive the essential components of work. Engage: Write around each of the following questions. • 1. What do you think physical work is? • 2. What factors do you think go in to making more or less physical work? • 3. If you could guess at what a work equation would equal, what would it be? 1 minutes • W =

8. Work Stations Continued Explore: Explore each stations and answer the explain questions for each. 16 min Station 1 Pulley Station. Station 7Elasticity Station 2 Lever Station. Station 3 Wheel & Axle Station Station 4 Pendulum Station Station 5 Screw Station 6Dominoes • Explain • Answer the following questions at each station… • How is this a demonstration of work being done? • b. What could be changed so that more work is done?

9. Work Stations Final Elaborate Work Class Discussion 1. Student groups write their equations of Work on the board (from Engage activity) 2. W= FΔx 3. Units: kgm2/s2 or Nm Evaluate 5. #E1 Work Practice

10. E#1 Work • A box that weighs 575 N is lifted a distance of 20.0m straight up by a cable attached to a motor. How much work is done by the motor? • Murimi pushes a 20 kg box 10 m across a floor with a horizontal force of 80N. Calculate the amount of work done by Murimi. • Lake Point Tower in Chicago is the tallest apartment building in the United States. Suppose you take the elevator from street level to the roof of the building. The elevator moves almost the entire distance at constant speed, so that it does 1.15x105J of work on you as it lifts the entire distance. If your mass is 60.0 kg, how tall is the building? Ignore the effects of friction. • A hummingbird has a mass of about 1.7g. Supose a hummingbird does 0.15J of work against gravity, so that it ascends straight up with a net acceleration of 1.2m/s2. How far up does it move? a. W=? F= 20N Δx=30m b. W=200 Nm F= ? Δx=60m c. W=0.50 Nm F= 3N Δx=?

11. Pinning It! Objective: Students will derive the essential components of work and potential energy. Engage What is energy? Come up with a definition for energy based on your current understanding of what energy is. 2. Today we will drive a push pin into a block of wood by dropping a ping-pong ball and a golf ball on it. Predict what will happen in each case, and give reasons based on the physics concepts that you’ve already learned like time, force, acceleration, velocity or momentum.

12. Explore & Explain Explore and Explain • Try to drive the push pin into the block then explain… a) How the activity shows connection to work. b) What would you do to do more work on the push pin? Elaborate Question: What is potential energy? What is kinetic Energy Short Lecture: Potential Energy -> Kinetic Energy -> Work Energy is transferred in this example so complete the sentence. Potential Energy is converted to _______ energy as the ball falls towards the pin. When the ball smashes into the pin it does _____ on the pin causing the pin to push into the wood. Draw a diagram of the activity where you will show the energy transfers and work being done. Evaluate 7. E#2 Potential Energy & Work

13. EH#2 Potential Energy & Work d. Ui=80J Uf=30J F=20N d=? m=20kg h=10m U=? Ui=80J Uf=? W=20J Ui=40 J Uf=10 J W=? • How much does the potential energy of a 2kg rock increase when you throw a rock straight up in the air and it reaches its maximum height 20 m above your head? • How much work did you do in problem 1? • What is the potential energy of a 400 kg anvil that is 10 meters above the ground? • How much work is done by gravity when a 12,000 kg meteor falls 10,000 m to earth and crashes?

14. E#3 Kinetic Energy & Work c Kf=50 Ki=100 J W=? F=20N Δx=? d. ΔK=80 J W=? F=? Δx=20m b. Kf=0 Ki=20 J W=200J • How much Kinetic Energy is gained when a 0.5 kg acorn drops from a tree branch 10 m high until the instant before it hits a stool 2m above the ground? - KE=39.2 J • Find the Force applied by a hammer on a nail if the hammer hits the nail with a Kinetic Energy of 8600 J and and the nail sinks 0.5 m into the wooden beam. - Fap=1.72x104 N a. Kf=0 Ki=100 J W=?

15. E#4 Work & Energy Conversions • Using 1000. J of work, a small object is lifted from the ground floor to the third floor of a tall building. How much potential energy did it gain? • A platform diver weighs 500 N. She steps off a diving board that is elevated to a height of 10 meters above the water. The diver will possess ___ Joules of kinetic energy when she hits the water. • A ball is projected into the air with 100 J of kinetic energy. The kinetic energy is transformed into gravitational potential energy on the path towards the peak of its trajectory. The kinetic energy at the peak of its trajectory is ______ Joules. When the ball returns to its original height, its kinetic energy is ____ Joules. • During a construction project, a 2500 N object is lifted high above the ground. It is released and falls 10.0 meters and drives a post 0.100 m into the ground. The average impact force on the object is ____ Newtons. • A 50-kg platform diver hits the water below with a kinetic energy of 5000 Joules. The height (relative to the water) from which the diver dove was approximately ____ meters. • Which requires more work: lifting a 50.0 kg crate a vertical distance of 2.0 meters or lifting a 25.0 kg crate a vertical distance of 4.0 meters?

16. This Too Shall Pass Picture Analysis • For each of the following pictures from the music video you just watched. • Draw the part of the picture where an energy transfer takes place. • Label the type of energy gained or lost (kinetic, potential, or work done) After drawing, pass your papers clockwise. Comment on the paper passed to you. • Identify one thing on the labeled drawing that you think is correct. • a. Explain why so that it will be easy for the paper’s owner to understand. • ii. Identify one thing on the labeled drawing that you would change. • a. Explain why so that it will be easy for the paper’s owner to understand.

17. HW E#5 If Mr. A (m=67.6 kg) is standing on a diving board 10 meter above the ground, what is his Potential Energy and Kinetic Energy when he is 10m, 7.5 m, 5.0m, and 2.5m and 0 m from the ground? 10m 7.5m 5.0m 2.5m Potential Energy = 0 Kinetic Energy =6625J 0m

18. E#5 Conservation of Energy If Mr. A (m=67.6 kg) is standing on a diving board 10 meter above the ground, what is his Potential Energy and Kinetic Energy when he is 10m, 7.5 m, 5.0m, and 2.5m and 0 m from the ground? 10m

19. E#6 Conservation of Energy A 70 kg person jumps from one stool to the next. a) Find the potential energy on each stool. The last stool falls down two meters when the person jumps jumps on it. b)How much potential energy did it lose? c) How much force does the person hit the stool with? a. • A 800 kg meteorite falls from the sky, hits the ground and makes a crater 800 m deep. a. How much work was done by the meteorite ? • How much kinetic energy did the meteorite gain from the long fall? • How high did the meteorite start out? 5m 3m 4m 2m 2. A car engine does 500 J of work. How much kinetic energy does the car gain if we assume that friction is negligible? A point guard bounces a 2kg basketball from 1.2 meters in the air. a. How much potential energy does it have? b. If the ball bounces back up only 0.7 m, how much energy was lost to the surrounding area. c. How much force should the basketball player apply in order to make the ball bounce back up to its initial height?

20. Kinetic Energy EH#7 • m=10kg v=2m/s K=? b. m=? v=6m/s K=70 J d. What is mechanical energy? What is the equation for Conservation of Mechanical Energy? When is mechanical energy not conserved? c. m=20 kg v=? K=100 J Calculate the kinetic energy of a 8kg object moving at a velocity of 4m/s. A 2000 kg car is traveling at 40 m/s, what is its kinetic energy? Three marbles (0.05 kg each) roll across the table with a speed of 2 m/s each in different directions. What is the total Kinetic Energy of this three ball system. A helicopter has 20,000 J of kinetic energy with a mass of 2000 kg. How fast is it moving?

21. Energy of Motion Lab Engage 1. What if we lowered the height of your ramp from yesterday. What effect would that have?” Explore 2. Take at least 5 data points, for different heights of the ramp and find the corresponding velocities at the bottom of the ramp. Explain 3. Graph the data in a way that makes sense to you and explain what knowledge you can get from the data. Elaborate 4. U= mgh, and ∆U= K. So instead of graphing height vs velocity, let’s graph K vsv

22. continue “How does v change with K? L a. Let’s square v and graph K vs. v2 and see what happens. • What kind of graph is this? What does the slope of the graph mean? • Linear y = m x + b • K = (½ m) v2 + 0 • Therefore, we have modeled that K = ½ m v2. • Note: Our data won’t be perfect because some energy is “lost” to rotation. Evaluate 7. E#7 on KE = ½ m v2

23. EH#8 Energy Transfer Practice A 6 g marble is rolled down a 5 m ramp. Assuming that friction and rotational energy lost are negligible, answer the following questions. • What is the initial potential energy of the marble? • What is the Total Mechanical Energy of the system? • What is the potential energy when the ball is 1.5 m above the ground? • What is the kinetic energy when the ball is 1.5 m from the ground? • What is the speed of the ball when it is 1.5 m from the ground? • What is the final kinetic energy of the ball? • What is the final speed of the ball?