Kinetic and potential energy problems
1. What is the kinetic energy of a jogger with a mass of 65.0 kg traveling at a speed of 2.5 m/s?
2. What is the mass of a baseball that has a kinetic energy of 105 J and is traveling at 10 m/s?
3. What is the kinetic energy of a 0.38 kg soccer ball that is traveling at a speed of 120 m/s?
4. What is the kinetic energy of a 0.50 kg ball travelling at a speed of 120 m/s ?
5. What is the kinetic energy of a 0.50 kg ball that is travelling at a speed of 40 m/s?
6. Find the gravitational potential energy of a light that has a mass of 13.0 kg and is 4.8 m above the
ground.
7. An apple in a tree has a gravitational potential energy of 175 J and a mass of 0.36 g.
How high from the ground is the apple?
8. A marble is on a table 2.4 m above the ground. What is the mass of the marble if it has a gravitational
potential energy of 568 J.
9. A box with a mass of 12.5 kg sits on the floor. How high would you need to lift it for it to have a GPE
of 355J ?
10. A cart at the top of a 300 m hill has a mass of40 kg. What is the cart’s gravitational potential energy?
11. Assuming that energy is conserved and there is no friction, at the bottom of the hill the cart’s
potential energy is completely converted to kinetic energy. Use the formula for kinetic energy to
calculate the cart’s speed at the bottom of the hill.
12. Two bullets have the mass of 3 g and 6 g, respectively. Both are fired with a speed of 40 m/s. Which bullet has more kinetic energy? What is the ratio of their kinetic energies?
13. Two 3 g bullets are fired with velocities of 40 m/s and 80 m/s respectively. What are their kinetic energies? Which bullet has more kinetic energy? What is the ratio of their kinetic energies?
14. A 40 kg child is in a swing that is attached to ropes 2 m long. Find the gravitational potential energy associated with the child relative to the child’s lowest position under the following conditions:
a) when the ropes are horizontal
b) when the ropes make a 30 degree angle with the vertical. (half off the ground)
c) at the bottom of the circular arc
15. A pinball bangs against a bumper, giving the ball a speed of 42 cm/s. If the ball has a mass of 50 g, what is the ball’s kinetic energy in joules?
16. A spoon is raised 21 cm above a table. If the spoon and its contents have a mass of 30 g, what is the gravitational potential energy associated with the spoon at that height relative to the table?
17. A 65 kg diver is poised at the edge of a 10 m high platform. Calculate the gravitational potential energy associated with the position of the diver. Assume the zero level is the surface of the pool.
18. What is the kinetic energy of a 1250 kg car moving at 45 km/hr?
19. A 25 kg falling object strikes the ground with a speed of 12.5 m/s. IF the kinetic energy of the object when it hits the ground is equal to the gravitational potential energy at some height above the ground, what is the height?