Question

A circular disc of mass 100 kg and radius of 0.8 makes 120 revolutions per minute calculate a) angular velocity
b) moment of Inertia about the axis of rotation

Answer 1

Answer:

Given:

Mass = 100 kg

Radius = 0.8 metres

Angular velocity in rpm = 120 rpm

To find:

1. Angular velocity in Radians/second

2. Moment of Inertia

Calculation:

Angular velocity

$= 120 \times \dfrac{2\pi}{60}$

$= 4\pi \: rad \: {s}^{ - 1}$

Moment of Inertia

$= \frac{1}{2} m {r}^{2}$

$= \frac{1}{2} \times 100 \times {(0.8)}^{2}$

$= 50 \times 0.64$

$= 32 \: kg \: { m}^{2}$

Answer 2

Answer:

Angular velocity:

=$120 \times \frac{2\pi}{60}$

=$4\pi \: rad \: s {}^{ - 1}$

moment of Interia:

=$\frac{1}{2} mr$

=$\frac{1}{2} \times 100 \times (0.8) {}^{2} .$

=$50 \times 0.64$

=$32 \: kg \: {m}^{2}$