Name: ____________________________ Date: ________________ Period: ________
Practice – Work/Power
1. What equation is used to solve for work?
2. What units are used for work? (Hint: There are 2 possible—write down both)
3. What is the physics definition of power?
4. What equation is used to solve for power?
5. What is the unit of power?
6. Where in your life have you seen this unit of power before?
For each situation below, decide if work is being done or not. Circle “YES” or “NO” for each
question.
YES
NO
Chris’ car is going 25 miles with the cruise control set at 45 mph.
YES
NO
Toni’s car accelerates from 0 mph to 60 mph over a distance of less than
a mile.
YES
NO
Carole stands still while holding her backpack.
YES
NO
An Olympic weightlifter holds 500 pounds of weight above his head.
YES
NO
A tug of war that is evenly matched.
YES
NO
A crane lifting a car.
For each situation below, decide if the work done on the second object has a positive or
negative value.
POSITIVE
NEGATIVE
The road exerts a friction force on a speeding car
skidding to a stop.
POSITIVE
NEGATIVE
A rope exerts a force on a bucket as the bucket is
raised up a well.
POSITIVE
NEGATIVE
Air exerts a force on a parachute as the parachutist
falls to Earth.
ICP
Name: ____________________________ Date: ________________ Period: ________
Please strictly follow the problem solving technique. This means every problem should include
all of these things:
1. Knowns/Unknowns
3. Plug & Chug
2. Equation with symbols
4. An answer with units
7. A tugboat pulls a ship with a constant net horizontal force of 5000 N and causes the ship
to move through a harbor. How much work is done on the ship if it moves a distance of
3000 m?
8. An apple has a mass of 0.18 kg
a. What is the force of gravity (or weight) on the apple?
b. If 2.0 J of work is done to raise the apple above, how far is it lifted?
9. You can pull a sled a total of 50 m with a force of 15 N
a. How much work have you done?
b. If it takes you 30 seconds to pull the sled, what power did you use?
c. If it takes you 120 seconds to pull the sled, what power did you use?
10. A force of 1 N moves a book 2 m.
a. Calculate the work done.
b. Calculate the power exerted in question 8 if it takes 3 seconds to move.
11. Calculate the power exerted when a 20 N force pushes a cart 3.5 m in a time of 0.5 s.
ICP