Question

Question 2 10 p 2. A pair of belted pulleys have diameters of 18 in. and 12 in. If the smaller pulley turns at 825 rpm, how fast will the larger pulley turn?

Answer 1

The two pulleys have diameters given as 12 inches (smaller) and 18 inches (larger).

If the smaller pulley can turn at a speed of 825 Rpm, then the larger one can turn as shown;

$\begin{gathered} \text{Ratio of both pulleys=12}\colon18 \\ \text{Ratio}=\frac{12}{18}=\frac{2}{3} \\ \text{For the speed of both pulleys, the ratio would be used as follows;} \\ \frac{2}{3}=\frac{825}{x} \\ \text{Cross multiply and you have,} \\ x=\frac{825\times3}{2} \\ x=1237.5 \\ x\approx1238 \end{gathered}$

The larger pulley will turn at a speed of 1,238 Rpm (approximately)