Question

Two particles \(A\) and \(B\) (both initially at rest) start moving towards each other under a mutual force of attraction. A the instant when the speed of \(A\) is \(v\) and the speed of \(B\) is \(2 v\), the speed of the centre of mass is
(A) Zero
(B) \(v\)
(C) \(\frac{3 v}{2}\)
(D) \(-\frac{3 v}{2}\)

Answer 1

Ans(A)

\begin{aligned}
&X \\
&u_{\text {com }} \bar{X}=0 \\
&\therefore \text { if } F=0 \text { then } \hat{v}_{\text {com }}=0 \text { always }
\end{aligned}