# A Wheel of Moment of Inertia 0⋅10 Kg-m2 is Rotating About a Shaft at an Angular Speed of 160 Rev/Minute. - Physics

Sum

A wheel of moment of inertia 0⋅10 kg-m2 is rotating about a shaft at an angular speed of 160 rev/minute. A second wheel is set into rotation at 300 rev/minute and is coupled to the same shaft so that both the wheels finally rotate with a common angular speed of 200 rev/minute. Find the moment of inertia of the second wheel.

#### Solution

Given

For the first wheel,

I1 = 10 kg-m2 and ω1 = 160 rev/min

For the second wheel, ω2 = 300 rev/min

Let I2 be the moment of inertia of the second wheel.

After they are coupled, we have

ω = 200 rev/min

If we take the two wheels to be an isolated system, we get

Total external torque = 0

Therefore, we have

$I_1 \omega_1 + I_2 \omega_2 = \left( I_1 + I_2 \right) \omega$

$\Rightarrow 0 . 10 \times 160 + I_2 \times 300 = \left( 0 . 10 + I_2 \right) \times 200$

$\Rightarrow 16 + 300 I_2 = 20 + 200 I_2$

$\Rightarrow 100 I_2 = 4$

$\Rightarrow I_2 = \frac{4}{100} = 0 . 04 kg - m^2$

Is there an error in this question or solution?

#### APPEARS IN

HC Verma Class 11, 12 Concepts of Physics 1
Chapter 10 Rotational Mechanics
Q 55 | Page 198