Work and Power Problems
Work problems
1. Calculate the amount of work done when moving a 567 N crate a distance of 20 meters.
2. A fallen tree with a weight of 5000 N is lifted 2.75 meters. How much work is done?
3. If it took a bulldozer 567.6 joules of work to push a mound of dirt 30.5 meters, how much force did the
bulldozer have to apply?
4. A frontend loader needed to apply 137 N of force to lift a rock. A total of 223 joules of work was done. How far
was the rock lifted?
5. A young boy applied a force of 2,550 N on his St. Bernard dog who is sitting on the boy’s tennis shoes. He was
unable to move the dog. How much work did he do trying to push the dog?
6. You must exert a force of 4.5 N on a book to slide it across a table. If you do 2.7 J of work in the process, how
far have you moved the book?
7. A child pulls a sled up a snow-covered hill. The child does 405 J of work on the sled. If the child walks 15 m up
the hill, how large of a force must the child exert?
8. How much work is done on a small car if a 3150 N force is exerted to move it 75.5 m to the side of the road?
9. A crate is being lifted into a truck. If it is moved with a 2470 N force and 3650 J of work is done, then how far is
the crate being lifted?
10. If 16,700 J of work is done to shoot the human cannonball down a 3.05 m barrel, then how much force is
applied to the person to fire them out the cannon?
Power Problems
11. A set of pulleys lifts a piano and does 3,356 joules of work. If the piano is lifted 75 seconds, how much power
is used?
12. How much work is done in order to cook a bag of popcorn in a 500 watt microwave for 5.5 minutes?
13. What is the power of an electric toothbrush if it can do 755.8 joules of work in 75 seconds?
14. Sara and josh do the exact same amount of work. Sara does the work in 2.3 hours and Josh does it in 2.4
hours. Who is more powerful? Explain.
15. How much power does it take to lift 30.0 N 10.0 m high in 5.00 s?
16. How much power does it take to lift 30.0 kg 10.0 m high in 5.00 s?
17. You do 45 J of work in 3.0 seconds. How much power do you use?
18. A car uses 2,500 Joules in 25 seconds. Find power.
19. A dock worker lifts a 375 N crate a distance of .5 m over his head in 2.3 seconds. What is his power output?
(*Hint: You must calculate something before you solve for power)