Question

A disc rotating about its axis with A angular speed ${\omega }_o$ is placed lightly (without any translational push) on a perfectly frictionless table. The radius of the disc is $R$.

Let $v_A,v_B$ and $v_C$ be the magnitudes of linear velocities of the points $A,B$ and $C$ on the disc as shown. Then

• A. $v_A>v_B>v_C$
• B. $v_A<v_B<v_C$
• C. $v_A=v_B<v_C$
• D. $v_A=v_B>v_C$

Answer 1

Answer: (D)

Velocity at point on the disc, $v=r\omega$
where $r$ is the distance of point from $O$.
$\therefore v_A=R{\omega }_0$
$v_B=R{\omega }_0$
$v_C=\frac{R}{2}{\omega }_0$
$\therefore v_A=v_B>v_C$