Question

The input work on a pulley system is 75 J. If the pulley system is 84 percent efficient, then what is the output work from the pulley system?

Answer 1

Answer: 63 J

Explanation:

The effiency ($E$) of a machine is given by the ratio between the output work $W_{out}$ and the input work $W_{in}$:

$E=\frac{W_{out}}{W_{in}}$

Where:

$E=84\%=0.84$

$W_{in}=75 J$

Isolating $W_{out}$:

$W_{out}=E W_{in}$

$W_{out}=(0.84)(75 J)$

Finally:

$W_{out}=63 J$