Question

Your family is moving. While lifting a box 1.5m upward to put it on a truck, you exert a force of 200N. How much work do you do?

Answer 1

Recall that power is the amount of work done per unit time,
P
=
W
t
When you're lifting a box, you're working against gravity. If you displace a box
1.5
m
in the positive direction, you're doing,
W
=
200
N
⋅
1.5
m
⋅
cos
(
0
°
)
≈
300
J
of work in one second.
Hence, the power required to execute this lift is approximately,
300
J
1.0
s
≈
300
W