Work and Power Practice
Directions: Answer the following questions on separate sheet of paper.
1. Define work.
Requires a force acting on an object in the same direction that it is moving.
2. What is the equation for work?
W=Fxd
3. Define power.
Power is a rate. It is the amount of work done in a given amount of time.
4. What is the equation for power?
P=
𝒘𝒐𝒓𝒌
𝒕𝒊𝒎𝒆
TRUE/FALSE
5. Power depends on how fast you do the work. True
6. Power is measured in Newtons. False -- Watts
7. Carrying an object is doing work. False -- lifting
8. Work is a form of energy. True
Directions: Determine whether work is done in the following situations.
9. You carry groceries inside your house.
No work
10. You give your sister a piggy back ride.
No work
11. You lift up box onto a table.
Work
12. You walk to school.
No work
Directions: Solve the following problems using the work and power equation. You must show your work and
include the correct units.
13. You must exert a force of 4.5 N on a book to slide it across the table. If you do 2.7 J of work in the process,
how far have you moved the book?
W=Fxd
W = 2.7 J
F = 4.5 N
d=?m
2.7 J = 4.5 N x d
d = 0.6 m
14. 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?
W=Fxd
W = 405 J
F=?N
d = 15 m
405 J = F x 15 m
F = 27 N
15. 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?
W=FxD
W=?J
F = 3150 N
d = 75.5 m
W = 3150 N x 75.5 m
W = 237,825 J
16. A 190,000 W engine can accelerate from rest to a top speed in 9 s. How much work did the engine do?
P=
𝒘𝒐𝒓𝒌
𝒕𝒊𝒎𝒆
P = 190,000 W
W=?J
t=9s
𝑾
190,000 W = 𝟗 𝒔
W = 1,710,000 J
17. Another engine reaches its top speed from rest in 7.5 seconds. It is able to perform 250,000 J of work in
that time. How much power does this engine have in that time?
P=
𝒘𝒐𝒓𝒌
𝒕𝒊𝒎𝒆
P=?W
W = 250,000 J
t = 7.5 s
P=
𝟐𝟓𝟎,𝟎𝟎𝟎 𝑱
𝟕.𝟓 𝒔
P = 33,333 W
18. If a runner exerts 350 J of work to make 125 W of power, then how long did it take the runner to do the
work?
P=
𝒘𝒐𝒓𝒌
𝒕𝒊𝒎𝒆
P = 125 W
W = 350 J
t=?s
125 W =
t = 2.8 s
𝟑𝟓𝟎 𝑱
𝒕𝒊𝒎𝒆