If a 3-inch drive pulley is spinning at 1720 RPM, what is the RPM of an 8-inch pulley?

To determine the RPM of the 8-inch pulley when the 3-inch drive pulley is spinning at 1720 RPM, you can apply the principle of rotational speed relative to the diameters of the pulleys. The relationship between the diameters of the pulleys and their rotational speeds is inversely proportional. This means that as the diameter of one pulley increases, its RPM decreases when driven by another pulley.

First, calculate the ratio of the diameters of the two pulleys:

• Diameter of the drive pulley (small pulley) = 3 inches
• Diameter of the driven pulley (large pulley) = 8 inches

Now, establish the ratio of the diameters:

[ \text{Diameter Ratio} = \frac{\text{Diameter of large pulley}}{\text{Diameter of small pulley}} = \frac{8}{3} ]

Since the speed is inversely proportional to the size of the pulleys, we can find the RPM of the larger pulley by using:

[ \text{RPM of large pulley} = \text{RPM of small pulley} \times \frac{\text{Diameter of small pulley}}{\text{Diameter of large pulley}} ]

Substituting the known values:

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