1000 2000 3000 4000 5000

1. 0 of 5 An object moving at 10m/s has 1000J of kinetic energy. The same object moving at 20m/s will have ______ J of kinetic energy. • 1000 • 2000 • 3000 • 4000 • 5000

2. 0 of 5 An object moving at 10m/s has 1000J of kinetic energy. The same object moving at 30m/s will have ______ J of kinetic energy. • 1000 • 3000 • 4000 • 6000 • 9000

3. 0 of 5 An object moving at 10m/s has 1000J of kinetic energy. The same object moving at _____ will have 250J of kinetic energy. • 1m/s • 2.5m/s • 5m/s • 10m/s • 25m/s

4. Jet Launcher • The Navy wants a new airplane launcher for their aircraft carriers and you are on the design team. The launcher is effectively a large spring that pushes the plane for the first 5 meters of the 20 meter long runway. During that same time, the plane's jet engines supply a constant thrust of 5.4 x 104 N for the entire length of the runway. The 2000 kg planes need to have a velocity of 45 m/s by the end of the runway. What should be the spring constant for the launcher?

5. Project • Build a set up with a cart and a spring. • Describe the different types of energy observed in the system. • Also describe the motion of the cart in terms of maximum and minimum displacement, velocity, and acceleration.

6. 4/3/07 Lesson #64Topic: Elastic Potential Energy Objectives: (After this class I will be able to) 1. Define spring force. 2. Define elastic potential energy. Warm Up: An archer aiming at a target draws an arrow back in his bow. While the archer is taking aim, what type of energy does the arrow have?

7. 0 of 5 An archer aiming at a target draws an arrow back in his bow. While the archer is taking aim, what type of energy does the arrow have? • Kinetic • Kinetic and gravitational potential • Gravitational potential • Elastic potential • Kinetic and elastic potential • Elastic and gravitational potential

8. Spring Force and Spring Constant • Elastic objects return to their original shape. • Springs and elastic objects exert a restoring force onto objects. • The strength of the spring depends on how much force is required to stretch the spring a certain distance. • k= spring constant • Fs= spring force • x= distance stretched or compressed

9. 0 of 5 What is the spring constant for a spring that stretches 10cm when 100g mass is hung from it? • 1N/m • 10N/m • 100N/m • 1000N/m • 10000N/m

10. 0 of 5 How much force is required to draw back a bow (k=1200N/m) 0.5m? • 600N • 1000N • 1200N • 2400N • 24000N

11. Elastic Potential Energy • When a force stretches or compresses a spring, work is done onto the spring. • This work is equal to the elastic potential energy of the spring. PEe=Ws • W=Fd where F is the average spring force (½ Fs) and d is the distance compressed / stretched (x). • Ws=½Fsx and if Fs=kx then Ws=½kx∙x

12. 0 of 5 How much work is done by compressing a spring 50cm if it has a spring constant of 10N/m? • 1.25J • 2.50J • 25J • 2500J • 12500J

13. 0 of 5 How much potential energy does an object have by compressing a spring 50cm if it has a spring constant of 10N/m? • 1.25J • 2.50J • 25J • 2500J • 12500J

14. 0 of 5 A spring has a relaxed length of 2.45m. When a 0.6kg mass is hung vertically from the end of it, the spring stretches to 3.57m. What is the PEe stored in the spring? • 3.36J • 6.72J • 13.4J • 25J • 45J

15. 0 of 5 Sam stands on a trampoline with a spring constant k=4667N/m. How much does the trampoline depress if Sam does 210J of work onto the trampoline? • 0.2m • 0.3m • 0.4m • 0.5m • 3m

16. 0 of 5 Sam has a mass of 70kg and jumps down onto the same trampoline so that it compresses 0.5m. How high above the trampoline does Sam fly? • 0.5m • 0.75m • 0.83m • 1.06m

17. 0 of 5 A 0.25 kg block on a vertical spring with spring constant of 5000 N/m is pushed downward, compressing the spring 0.1m. When released, the block leaves the spring and travels upward vertically. How high does the block rise above point of release? • 1m • 4m • 7m • 10m

18. Jet Launcher • Write a neatly written statement to the commander of the aircraft carrier explaining the steps of your calculations when finding what the spring constant should be for the new jet launcher.

19. 0 of 5 Jane is looking for Tarzan, is running at top speed 5.6m/s and grabs a vine hanging vertically from a tall tree in the jungle. How high can she swing upward? • .28m • .98m • 1.57m • 15m

20. 0 of 5 A roller coaster is pulled up to a point where its screaming occupants are released from rest 30m above the lowest dip in the ride. What is the velocity of the coaster at this lowest point? • 20m/s • 24.5m/s • 26.8m/s • 600m/s

21. 0 of 5 A roller coaster is pulled up to a point where its screaming occupants are released from rest 30m above the lowest dip in the ride. What is the velocity of the coaster at the top of the next hill that is 25m above the lowest point? • 10m/s • 15m/s • 20m/s • 100m/s

22. 0 of 5 A roller coaster is pulled up to a point where its screaming occupants are released from rest 30m above the lowest dip in the ride. What is the velocity of the coaster on a straightaway that is 12m above the lowest point? • 12m/s • 15m/s • 19m/s • 21m/s

23. 0 of 5 A 75kg trampoline artist jumps vertically upward from the top of a 3m high platform with a speed of 5m/s. If the trampoline acts as a spring where k= 5.2x104N/m, how far does he depress the trampoline? • 0.12m • 0.35m • 0.82m • 1.2m

24. 0 of 5 A 17kg child descends a slide 3.5m high and reaches the bottom with a speed of 2.5m/s. How much energy was “lost” due to friction? • 0.57J • 53J • 542J • 595J

25. 0 of 5 A 0.2kg pinecone falls from a branch 18m above the ground. It hits the ground with a speed of 10m/s. What was the average force of air resistance exerted on it? • 10J • 26J • 1.44N • 2.01N

26. Conservation Quiz #5 A C 30m D 25m B 12m

27. 0 of 5 Which of the following situations is work done onto the book by Joe? • Joe holds a 1kg book 2m above the ground. • Joe carries a 1kg book across the room at constant speed. • Joe lifts a 1kg book from the floor to 2m high. • Both 1 & 2

28. 0 of 5 A ball is tossed vertically into the air. It has maximum kinetic energy when • It first leaves the throwers hand • It is landing in the throwers hand • It is at its highest point • Both 1 and 2

29. 0 of 5 A slingshot is pulled back an extra distance and then fired. The projectile will travel further because of • The force will be applied for a longer amount of time. • The force will be applied throughout a longer distance. • The force will be greater. • All of the above.

30. 0 of 5 A car traveling at 20 km/h skids 20 m to a stop when the brakes are locked. How far will the same car travel after the brakes are locked if it is initially traveling 40 km/h? • 20m • 40m • 60m • 80m

31. 0 of 5 A rollercoaster climbs a steep hill and is released from rest before falling to its lowest point and then climbing a smaller hill. The rollercoaster has the most total energy • at the top of the first hill • at the top of the second hill • at its lowest point after the first hill • the total energy of the coaster remains constant.

32. Modern Art • Your artist friend is designing a kinetic sculpture and asks for your help since she knows that you have had physics. Part of her sculpture consists of a 6.0-kg object (you can't tell what it is supposed to be, but it's art) and a 4.0-kg object which hang straight down from opposite ends of a very thin, flexible wire. This wire passes over a smooth, cylindrical, horizontal, stainless steel pipe 3.0 meters above the floor. The frictional force between the rod and the wire is negligible. The 6.0-kg object is held 2.0 meters above the floor and the other object hangs 0.50 meters above the floor. When the mechanism releases the 6.0-kg object, both objects accelerate and one will eventually hit the floor -- but they don't hit each other. To determine if the floor will be damaged, calculate the speed of the object which hits the floor.