Practice Problems – Work
Practice Problems – Power
1. A person uses a force of 7 N to drag a garbage can a distance of 15 m.
How much work is done on the garbage can?
2. 20 N∙m of work is done on a desk, which is pushed a distance of 5 m.
How much force is exerted on the desk?
3. A force of 6 N pushing on a crate produces 48 N∙m of work. How many
meters did the crate move?
4. An average golfer’s golf club can reach a velocity of 41 m/s in as little as
.19 seconds. A golf ball has a mass of 0.045 kg. How many joules of work
are done on a golf ball by a golfer who hits a golf ball 80 m?
5. Two people push against a stalled car. If each person pushes with a force
of 25 N, how far will the car move if the total work done is 140 J?
6. A carton of books that weighs 25 N is lifted to a height of 6 m above the
ground. How much work was required to lift the books?
7. A piece of furniture that weighs 500 N is pushed along the ground for a
distance of 10 m, then lifted 2 m above the ground into a truck. How
much work is done if the force required to push the furniture is 150 N?
8. A 25 kg child is lifted to a height of 7 m above the ground. How much
work is required to lift the child?
9. One hundred joules of work is required to push a piano across the stage.
How much force is needed to move the piano if the stage is 20 m wide?
W
F
2. An elevator lifts a person weighting 625 N a distance of 7 m. If the
elevator uses 875 W of power to lift the person, how long does it take?
3. A machine uses 26 W of power. How much work does the machine do in
a minute?
4. A person takes 9 seconds to drag a 45 N box across a road. If the person
uses 125 W of power, how wide is the road?
5. An elevator takes 8 seconds to rise 8 meters off the ground. If the power
used by the elevator is 6,560 W, how much does the elevator weigh?
6. A person takes 40 seconds to push a wheelbarrow a distance of 25 m.
How much force does the person exert if the total power expended is 50
watts?
7. An automobile weighing 10,000 N moves 500 meters in 5 seconds. How
much power is used by the automobile?
8. Two horses pull a wagon full of hay. If each horse pulls with a force of
2,500 N and the wagon moves a distance of 250 m, how much power is
used by each horse if the wagon is in motion for 5 seconds?
9. A 60 kg person and a 70 kg person climb 9 m up a flight of stairs in 10
seconds. Compare the power used by each person.
10. A pulley does 500 J of work and uses 50 watts of power to lift a load 10
meters off the ground. Then a crane lifts the same load an additional 25
meters. What is the total amount of power
used to lift the load if the total time is
30 seconds?
W
10. A 6 kg bag of groceries is lifted a distance of 1.5 m, then carried a
distance of 1 km. How much work is done on
the bag of groceries?
11. Wil Wheaton bench presses 90 kg of weights
0.60 m into the air, and then returns the weights
to the exact position before the weights were
lifted. How much work was done
on the weights?
1. A crane lifts a load weighting 10 N through a distance of 8 m. If it takes
the crane 5 seconds to complete the task, how much power does the
crane use to lift the load?
d
P
t