Langhoff Work and Power Study Guide Name______________________________________ 1. Define power: 2. Define work: 3. Define force: 4. What is the unit for Power ___________ Work _______________ Force ____________ 5. Calculate the work done by a 35 N force pushing a pen 0.26 m. 6. If you have done 345 Joules of work on a cabinet, with a 75 N force, what distance did you move the cabinet? 7. Calculate the work done by a 47 N force pushing a pencil 0.25 m against a force of 23 N. (Find net force first) 8. Calculate the work done by a 2.4 N force pushing a sandwich across a table 0.75 m wide. 9. What work is necessary to pull a 400 N wagon over a distance of 50 meters? 10. How much power does it take to lift 30.0 N 10.0 m high in 5.00 s? (Find work first) 11. How much power does it take to lift 20.0 kg 20.0 m high in 5.00 s? ( Find force or weight first w=mg, then work, then power) 12. You do 45 J of work, with a power of 15 Watts how long did it take you? Langhoff 13. A car uses 2,500 Joules in 25 seconds. Find power. 14. A horse performs 15000 joules of work pulling a wagon for 20 seconds. What is the horse's power? 15. A 750 watt hairdryer is used for 60 seconds. How many joules of energy are used? 16. The power rating of an electric lawn mower is 2000 watts. If the lawn mower is used for 120 seconds, how many joules of work can it do? 17. How much work is done when you use 1300 watts of power for 35 seconds? In the following problems state whether work was done. Put a “W” for work done and a “N” for not work done. 18. You lift a 120 N box 2 meters off the ground _______________ 19. You are coasting on you bike at 5 mph over a distance of 100 meters. ________________ 20. Your friend is holding your 75 N textbooks for you. _________________ 21. The 2 N football is flying through the air for 35 yards. _______________ 22. You are pulling a 300 N couch up a ramp that is 3 meters long. ____________