WORK, POWER, AND ENERGY
1. A person is performing a lift against a 400 N load. The load moves vertically through a distance of 20
cm in a time of 0.25 s.
(a) How much work was done on the load?
(b) What is the person's average power during the lift?
(c) What is the load's increased potential energy after the lift?
2. If the load mentioned above was moving at 7.0 m/s after moving 10 cm, what was its total energy,
kinetic energy, and potential energy at this point (assume that the load started 50 cm from the ground)?
3. How high will a 30 kg object travel after it is released if it is released with a vertical velocity of 2.0
m/s?
4. How much power is present when a force of 500 N is applied to an object with a mass of 100 kg that is
moving at 6 m/s?
5. What work is done when an object is lowered 1.80 m if the object has a mass of 700 kg?
6. What is the impulse delivered to a catcher's mitt by a 360 g ball that is traveling at 100 km/h and is
then stopped by the catcher in .01 s?
7. How high would you have to drop an 80 N object so that it will have a kinetic energy of 2000 J when it
hit the ground?
8. A 55 kg person moves at the constant speed of 7 m/s along a straight stretch of track. What is the
person's:
(a) acceleration
(b) momentum
(c) kinetic energy
9. How much work is done to stop an 90 kg football player who is running at 8.5 m/s, horizontally, and
you do not have to knock him down?
10. What is the work done by a force of 500 N that acts at an angle of 25 degrees to an object and that
moves the object a displacement of 12 m?
11. Dino Dude is peacefully floating over the water when a big blue bird pops his balloons, causing Dino
Dude to fall 10 m before crashing into the water. If Dino Dude has a mass of 20 kg, what is his velocity
immediately before impact with the water?