Answer
12.5 rotations
Work Step by Step
1. We take the given rate of pulley and convert it to degrees per hour
$\frac{75^{\circ}}{1min}$$\times$$\frac{60min}{1hr}$ = 4500$^{\circ}$/hr
2. To find number of rotations in one hour, we need to divide the total number of degrees by 360:
$ \frac{4500^{\circ}}{1hr}\times$$\frac{1 rot}{360^{\circ}}$ = 12.5 rotations/ hour
Therefore, in one hour 12.5 rotations