Work/nergy 1. student throws a ball upward where the initial potential energy is 0. t a height of 15 meters the ball has a potential energy of 60 joules and is moving upward with a kinetic energy of 40 joules. Ignoring air resistance, the maximum height achieved by the ball is most nearly () 10 m () 0 m () 5 m () 30 m () 40 m. box of mass m is lifted a vertical distance h in time t with a constant velocity. The power supplied by the lifting force is approximately () mght () mgh/t () zero () mgt/h () mg/ht 3. crate is lifted by a force F which is greater in magnitude than the crate s weight W. The change in kinetic energy of the crate during this time is equal to the () work done by the net force (F - W) () work done by F () work done by W () the change in momentum of the rock before and after this time () the change in the potential energy of the rock before and after this time. 4. constant force supplies an average power of 8 watts to a box during a certain time interval. If the box has an average speed of 4 meters per second and the force acts in the same direction as motion of the object, the magnitude of the force is () 8 N () 6 N () 4 N () N () 1N 5. pencil is moved from point to point along a curved path. The work done by the gravitational force on the pencil depends on which of the following: () the velocity of the object as it moves between and () the positions of points and () the path taken between and () both the positions of and and the path taken between them () the nature of the external force that moves the object from to 6. man lifts a mass m at constant speed to a height h in time t. How much work is done by the man? () mgt () zero () mgh () mgh/t () cannot be determined
7. 3 m long frictionless pendulum of swings with an amplitude of 10. t its equilibrium position the kinetic energy of the pendulum is 0 J. What is the potential energy of the pendulum when the kinetic energy is 5 J? () 3.3 J () 5 J () 6.7 J () 10 J () 15 J 8. On top of a 300-meter-high skyscraper, a -kilogram ball is thrown directly downward with an initial speed of 0 meters per second. If the ball reaches the ground with a speed of 60 meters per second, the energy lost to friction is approximately () 0J () 1800 J () 300 J ( ) 800 J () 3300 J Questions 9-10 spring has a spring constant of 100 N/m and is 0.1 m long when unstretched. One end is attached to a center post that is free to rotate on a frictionless table top. The other end is attached to kg disc moving in uniform circular motion, which stretches the spring by 0.05 m. 9 What is the centripetal force on the disc? () 0.5 N () 5 N () 10 N () 500 N () 1,000 N 10. What is the work done on the disc by the spring during one full circle? () 0 J () 0.5 J () 186 J () 314 J () 68 J 11. student pushes a box across a rough, flat surface at a constant speed of 1 meter per second. The box has a mass of 50 kilograms, and the coefficient of sliding friction is 0.. The power supplied by the student to the box is () zero () 5 W () 50 W () 100 W () 00 W L 45 1. ball of mass m suspended at the end of a massless string of length L as shown above. This pendulum is lifted to a 45 angle with the vertical and released. t the low point of its swing, the speed of the ball is () gl () gl () - )gl ( () gl () 1/gL
M 13. n ideal massless spring is fixed to a wall at one end, and attached to a block of mass M on the other end. The spring oscillates with amplitude on a frictionless, horizontal surface. The maximum speed of the block is vm. The spring constant of the spring is () Mg () Mg () Mv m () Mv m () Mv m M1 M 14. When the object of mass m1 descends to a distance h, the potential energy of the system has decreases by () (m1 m)gh () m1gh () (m1 + m)gh () ½(ml + m)gh () 0 Questions 15-0 cart of mass M travels along roller coaster that is shown above. It consists of a frictionless ramp of height 4R connected to a frictionless loop of diameter R and a frictionless hill of height R. fter the hill it comes to a frictionless horizontal track collides with a spring with a force constant K that is attached to the wall. fter the collision with the spring the cart compresses the spring and stops at point. 15. t which point is the potential energy of the cart the greatest? () Point () Point () Point () Point () Point 16. t which point is the kinetic energy of the cart the greatest? () Point () Point () Point () Point () Point
17. How fast is the cart traveling at Point? () gr () gr () 3gR/ () 6gR () gr 18. t Point what is the direction of the cart s acceleration? () () () () () None 19. etermine the cart s acceleration at Point () 0.5 g () g () g () 4g () None 0. What is the maximum compression in the spring? () mgr/k () mgr/k () mgr/k () mgr/k () 8mgR/k cart of mass M travels along roller coaster that is shown above. It consists of a frictionless ramp of height 4R connected to a frictionless loop of diameter R and a frictionless hill of height R. fter the hill it comes to a rough horizontal track. 1. What is the coefficient of kinetic friction so that the cart stops at the end of the rough track? () 0.5 () 0.5 () 1 () () 4
. 5 kilogram block is pushed horizontally across a rough surface with a coefficient of kinetic friction of 0. by a force F moving at 3 m/s. The work that is done by the force in 0 seconds is () 00 J () 400 J () 600 J () 800 J () 1000 J Question 3-5 1 5 5 m 4 ball swings from a simple pendulum in simple harmonic motion as shown above. 3. t which point is the kinetic energy of the ball at maximum? () Point 1 () Point () Point 3 () Point 4 () Point 5 4. What happens to the potential energy as the ball passes from point 3 to point 4? () increases () decreases () stays the same () zero () not enough information 5. What is the velocity at its lowest point? () 0 m/s () m/s () 5 m/s () 8 m/s () 10 m/s Questions 6-8 3 metal sphere of mass m is tossed from a cliff of height h with an initial velocity vi. 6. What is the total energy of the ball at the top of the cliff? () 0 () mgh () ½ mvi () mgh-½ mvi () mgh+½ mvi 7. What is the total energy of the ball halfway through its fall? () 0 () mgh/ () ½ mvi () mgh/+½ mvi () mgh+½ mvi 8. What is the kinetic energy of the ball at the bottom of the cliff? () 0 () mgh () ½ mvi () mgh-½ mvi () mgh+½ mvi 9. spring gun of spring constant k launches a ball of mass m off a cliff of height h. If the velocity of the ball right before it hits the ground is v. How much was the spring compressed? () 0 () mgh () ½ mv () m( v gh)/k () mgh/k
30. 10 kg block is raised 5 m at a constant speed of m/s by a crane. The power supplied by the crane is (use g=10 m/s ): () 00 W () 10 W () 0 W () 5 W () 50 W 31. -kg mass accelerates 10 m across a frictionless surface by a 40 N force as shown in the figure above. The work done over this interval is: () 10 J () 00 3 J () 10 3 J () 10 J () 00 J 3. 8 kg mass is attached to a light string 4 m long and hung vertically to make a simple pendulum. The pendulum is displaced until the string is horizontal and then released. What is the approximate speed of the pendulum at its lowest point? () 5 m/s () 7 m/s () 9 m/s () 10 m/s () 11 m/s 33. 60 kg mass is dropped from a roof, which is 5 meters above a spring platform of negligible mass. When the mass lands on the platform, it drops 5 m before it comes to rest. What is the spring constant of the spring? () 10 N/m () 150 N/m () 00 N/m () 40 N/m () 300 N/m Problems 34-35: 34. The graph represents the force exerted on a particle. What is the work done on the object from x=0 to x= 4 m? () 8 J () 10 J () 15 J () 16 J () 0 J 35. What is the work done on the object from x=0 to x=6 m? () 4 J () 6 J () 10 J () 1.5 J () 5 J
36. Which of the following is an accurate statement? () Potential energy is always negative. () Total energy is always positive. () uring simple harmonic motion, the kinetic energy is always equal to the potential energy. () Kinetic energy is always positive. () None of these is true. Question nswer Question nswer 1. 19.. 0. 3. 1. 4.. 5. 3. 6. 4. 7. 5. 8. 6. 9. 7. 10. 8. 11. 9. 1. 30. 13. 31. 14. 3. 15. 33. 16. 34. 17. 35. 18. 36.