Question

Jill can use a force of 12.0 N to lift a single box up 5.00 m. How many of these boxes must she lift it in a minute to use 60.0 W of power?

Answer 1

60 boxes

Step-by-step explanation:

The work done by lifting a single box is equal to the force applied (the weight of the box) times the displacement of the box:

`W_1 = Fd=(12.0 N)(5.00 m)=60 J`

Power is related to the work done by the equation:

`P=(W)/(t)`

where W is the work done and t is the time. In this problem, we are told that the power used is P=60.0 W, while the time taken is t = 1 min = 60 s, so the total work done must be

`W=Pt=(60.0 W)(60 s)=3600 J`

Therefore, the number of boxes that she has to lift in order to use this power is the total work divided by the work done in lifting each box:

`N=(W)/(W_1)=(3,600 J)/(60 J)=60`