Use the Following Diagram for the Next Three Questions

Name ______period ______2nd 9 weeks physics test review Due Monday 12/ 14/ 2015

USE THE FOLLOWING DIAGRAM FOR THE NEXT THREE QUESTIONS.

A ball is kicked at a 50o angle. The initial horizontal velocity is 10m/s and the initial vertical velocity is 15m/s. 1. What is the magnitude of acceleration at each point: A, B, and C?

2. What is the horizontal velocity at each point?

3. At which point (A, B, or C) will the football have the smallest vertical velocity? Why?

4. Explain how decreasing the radius of the loop of a roller coaster increases the acceleration of the riders. 5. Use the picture below to answer the questions.

a. Using the height formula: how long will it take for the ball to hit the ground?

b. Using the formula x=voxt, what is the velocity of the launch?

6. On the picture below, label the centripetal acceleration, the radius, and the tangential velocity. 7. Look at the question below to answer the problem.

a. If the three rocks above, A, B, and C, were all thrown off a cliff at the same time, which would hit the ground first and why?

8. If two masses, 5kg and 10 kg respectively, have a force between them of 0.005N, what 2 is the greatest distance between them? ( hint: find r using F= Gm1m2/r )

9. A comet is heading towards Earth. If the original distance is cut in half, and the mass of the comet is reduced to 1/3 its original mass, what is the new force between the comet and the earth? (hint: see nots on using F to find F’) 10. Which is the action force, and which is the reaction force: a. ______The gravitational pull attracting the comet to the Earth b. ______The gravitational pull of the comet pulling the Earth towards the comet.

11. A student uses 15N of force to push a box 5m in 20seconds. a. What is the magnitude of work done on the box? (hint: W=Fd)

b. What is the student’s power output? (hint: P=W/t)

12. Identify each as either an example of kinetic energy transformed to potential energy (KE to PE) OR potential energy transformed to kinetic energy (PE to KE) a. ______A ball released from a catapult b. ______A ball rolling up a hill

c. ______Bending a paper clip

d. ______Coasting down a hill on a bicycle e. ______Starting an automobile engine f. ______Jumping out an airplane g. ______Driving towards a stop sign 13. True or false: the greater the force exerted by a student on a bike over a set distance, the greater the change in kinetic energy. Explain why.

14. Why doesn’t velocity contribute to the potential energy of an object?

15. It takes 500J of work to stop a 1000kg moving car. What was the initial velocity

of the car? (hint: W= KEf - KEi)

16. It takes 200J of work to get a car initially at rest to move. What was the final

speed of the car? (hint: W= KEf - KEi) 17. I come to class saying I have created a new energy that will help save the world. Do you believe me? Why or why not?

18. What is the potential energy of a 10kg weight suspended 10m above the ground? (hint: GPE= mgh)

19. Look at the table below to answer the questions. Runner Distance Time of travel traveled #1 100m 40s #2 150m 20s #3 200m 15s a. Which runner was the most powerful? Why? 20. Use the picture below to answer the problem. (hint: you can have more than one answer; ME= GPE + KE)

a. ______Where do you have the greatest Mechanical Energy?

b. ______Where do you have the greatest GPE?

c. ______Where do you have the greatest KE?

d. ______Where will you have the greatest velocity?

21. Katniss uses 150, 000J of Kinetic energy to pull the bow back 0.70meters. How much elastic energy has she stored in the bow? (hint: EPE=1/2 kx2)