Name:______Date:______Hour: 1 2 3 4 5 6
Work and Power Practice
Directions: SHOW ALL NECESSARY STEPS AND WORK (GUESS method) on a separate sheet of paper. Answers are in italicized parenthesis so you can check your work and understand the process.
WORK
1) How much work is done when you lift a 24 kg mass 5 m? (1176 J)
2) If you exert 1850 N to do 3100 J of work on a refrigerator, how far did you move it? (1.68 m)
3) What is the mass of an object if it took 264 J to lift it 12 m? (2.24 kg)
4) A child does 405 J of work to pull a sled up a hill. If the child walks 15 m up the hill, what force is required? (27 N)
5) 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? (0.6 m)
6) How much work is done on a car if a 3150 N force is exerted to move it 75.5 m to the side of the road? (237,825 J)
7) How much force is necessary to push a car 8.2 m and do 12,400 J of work? (1,512.2 N)
8) A crate is being lifted into a truck. If it is moved with a 2470 N force and 3650 J of work is done, how far has the crate been lifted? (1.48 m)
9) What is the mass of an object if it took 270 J of work to lift it 15 meters? (1.84 kg)
10) What is the mass if the work is 372 J and the object is lifted 16 m? (2.37 kg)
11) 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? (5,475.4 N)
12) An elephant pushes with 2000 N on a load of trees for 150 m. how much work did the elephant do? (300,000 J)
13) How much work is done by a crane that lowers 1,000 Newtons of material a distance of 150 meters? (150,000 J)
14) If you do 490 J of work to lift a book 3 m, how much force was required? (163.3 N)
15) How much work is done to carry a 20 N book 5 m across the room? Explain. (0 J)
POWER
16) How much power is needed to do 648 Joules of work in 100 seconds? (6.48 W)
17) How long does it take to do 278 Joules of work with 17 watts? (16.35 s)
18) If 270 watts of power is used in 42 seconds, how much work was done? (11,340 J)
19) How much work was done if you use 75 W for 500 s? (37,500 J)
20) How much time is needed to do 4.2 J of work with 0.8 W of power? (5.25 s)
21) How much power does it take to do 900 J of work in 4 s? (225 W)
22) How long does it take to do 326 J of work with 16 watts? (20.375 s)
23) If you use 1100 W of power for 37 seconds, how much work is done? (40700 J)
24) How long does it take to do 46 J of work with 7 W of power? (6.57 s)
25) How much work is done if you use 242.5 W for 916.3 s? (222,202.75 J)
26) A 190,000 W engine can accelerate from rest to top speed in 9 s. How much work did the engine do? (1,710,000 J)
27) How long does a 1,200,000 W engine have to burn to do 35,000,000 J of work? (29.17 s)
28) How much power is used to do 710.8 J of work in 290.2 s? (2.45 W)
29) If a runner exerts 350 J of work to make 125 W of power, then how long did it take to do that work? (2.8 s)
30) If you light a 60 W light bulb for 4.2 s, how much work did you do? (252 J)
WORK AND POWER
31) If 478 watts of power are used in 14 seconds, how much work was done? (6,692 J)
32) How long does it take to do 432 joules of work with 75 watts of power? (5.76 s)
33) How much power is used to lift a 25 kg mass 8 meters in 15 seconds? (130.7 W)
34) If it takes 726 watts of power to lift a mass 36 meters in 14 seconds, what is the mass? (28.81 kg)
35) If an object has a mass of 47 kg and it is lifted 27 meters in 60 seconds, how much power was used? (207.27 W)
36) How much power is used to lift a 5 kg mass 28 meters in 8 seconds? (171.5 W)
37) If an object with a mass of 245 kg is lifted 76 meters in 18 seconds, how much power is used? (10,137.6 W)
38) How long would it take to lift an 11 kg object 6 m with 42 W of power? (15.4 s)
39) How much power is needed to lift a 7 kg mass 14 m in 16 seconds? (60.0 W)
40) How much power do you use to walked forward 7 meters in 3 s while holding a 14 kg box? (0 W)
41) A student who weighs 500 N climbed the stairs from the first floor to the third floor, 15 m above, in 20 seconds. A) How much work was done? B) What is the power used? (7,500 J, 375 W)
42) A 5 kg rock is lifted 2 m in 5 s. A) How much work is done? B) What power is used? (98 J, 19.6 W)
43) An elevator lifts 5 passengers 30 m in 24 s. The power is 15,000 W. What is the total weight moved? (12,000 N)
44) A 79 newton rock is lifted 1.85 meters in 4.7 seconds. A) How much work is done? B) What power is used? (146.15 J, 31.1 W)
45) A student who weighs 400 N climbed the stairs from the first floor to the third floor, 15 meters above, in 16 seconds. A) How much work did she do? B) What was her power? How can she do the same work and use different power as the student in #41? (6000 J, 375 W)
46) A woman lifts a 300 newton child a distance of 1.5 meters in 0.75 seconds. What is her power output? (600 W)