Question

A circular disc rotates in a vertical plane about a fixed horizontal axis which passes through a point $X$ on the circumference of disc. When the centre of the disc moves with speed $v$, the speed of the opposite end of the diameter through $X$ is

• A. $2v$
• B. $\sqrt{2}v$
• C. $v$
• D. $v/2$

Answer 1

The correct option is A $2v$

Let $w$ be the angular velocity about point X.

$V_C=Rw⟹v=Rw$

$V_A=\left(2R\right)w=2v$