A circular metal disc of mass 200g and radius 20cm makes 10 revolutions per second about an axis passing through the centre and perpendicular to its plane. Find a) Moment of inertia about to axis, b) Torque required to change its angular velocity from 10 rps to 20 rps in 5s.

A circular metal disc of mass 200g and radius 20cm makes 10 revolution

1.	A circular metal disc of mass 200g and radius 20cm makes 10 revolutions per second about an axis passing through the centre and perpendicular to its plane. Find a) Moment of inertia about to axis, b) Torque required to change its angular velocity from 10 rps to 20 rps in 5s.
Answer» SOLUTION :`(a) I=(Mr^(2))/(2)=(0.2xx(0.2)^(2))/(2)=4xx10^(-3)kgm^(2)` (B) Torque `TAU=Ialpha=(I(omega_(2)-omega_(1)))/(t)` `:.tau=(4xx10^(-3)(40pi-20pi))/(5)`, `tau=0.05Nm`