Work and Power Calculations
Even More Math??
Work
Work occurs when a force causes an
object to move in the direction of the
force applied.
Work Formula
Work = Force X Distance
Work = Newtons X Meters
Units = Joules (J)
Work Calculation Example
A man applies a force of 500.0N
to push a truck 100.0m down
the street. How much work
does he do?
W=FXD
W = 500.0 N X 100.0 M
W = 50,000.0 J
Work Problem 1
You push a 75.0N box 3.0m
across the floor. How much work
has been done?
W=FXD
W = 75.0N X 3.0m
W = 225.0J
Work Problem 2
Amy used 20.0N of force to push
a lawn mower 10.0m. How
much work does she do?
W=FXD
W = 20.0N X 10.0m
W = 200.0J
Work Problem 3
How much work is done by a
person who uses a force of
27.5N to move a grocery cart
12.3m?
W=FXD
W = 27.5N X 12.3m
W = 338.3J
Work Calculation 4
Calculate the amount of work
done when moving a 567.0N
crate 20.0m.
W=FXD
W = 567.0N X 20.0m
W = 11340.0J
Work Calculation 5
A basket of apples weighs
12.0N. If the basket is lifted
0.8m, how much work is
being done?
W=FXD
W = 12.0N X 0.8m
W = 9.6J
Power
The rate at which work is done.
Power Formula
Power = Work / Time
Power = Joules / Seconds
Units = Watts (W)
Power Calculation Example
What is the power of a small
motor that can do 4500.0J of
work in 25.0 seconds?
P=W/T
P = 4500.0J / 25.0s
P = 180.0W
Power Problem 1
What is the power of an engine
that can do 1500.0J of work in
75.0 seconds?
P=W/T
P = 1500.0J / 75.0s
P = 20.0 W
Power Calculation 2
What is the power of a motor that
can do 15.5J of work in 2.3
seconds?
P=W/T
P = 15.5J / 2.3s
P = 6.7W
Power Calculation 3
What is the power of a motor that
can do 2000.0J of work in 1.5
seconds?
P=W/T
P = 2000.0J / 1.5s
P = 1333.3W