Question

A potter's wheel is rotating around a vertical axis through its center at a frequency of 1.5 rev/s . The wheel can be considered a uniform disk of mass 4.7 kg and diameter 0.36 m . The potter then throws a 2.8-kg chunk of clay, approximately shaped as a flat disk of radius 7.0 cm , onto the center of the rotating wheel. What is the frequency of the wheel after the clay sticks to it? Ignore friction.

Answer 1

Moment of inertia of the potter wheel I = (1/2) MR ²

          I = 0.5 x4.7 x0.36 ²

            = 0.30456 kgm 2

Frequency f = 1.5 rev/s

Moment of inertia of the potter wheel after throw chunk clay I ' = I +mr 2

I ' = 0.30456 +(2.8 x0.07 ² )       Since r = radius of clay = 7 cm = 0.07 m

    = 0.31828 kg m ²

the frequency of the wheel after the clay sticks to it f ' = ?

If = I ' f '

From this f ' = If / I '

                   = 1.435 rev/s