A goods train accelerating uniformly on a straight railway track, approaches an electric pole standing on…

A goods train accelerating uniformly on a straight railway track, approaches an electric pole standing on the side of track. Its engine passes the pole with velocity $u$ and the guard's room passes with velocity $v$. The middle wagon of the train passes the pole with a velocity.
  1. $\frac{u+v}{2}$
  2. $\frac{1}{2} \sqrt{u^2+v^2}$
  3. $\sqrt{u v}$
  4. $\sqrt{\left(\frac{u^2+v^2}{2}\right)}$

Solution

Let ' $S$ ' be the distance between two ends ' $a$ ' be the constant acceleration As we know $V^2-u^2=2 a S$ or, $a S=\frac{V^2-u^2}{2}$ Let $V$ be velocity at mid point. Therefore, $V_c^2-u^2=2 a \frac{S}{2}$ $ \begin{aligned} & V_c^2=u^2+a S \\ & V_c^2=u^2+\frac{V^2-u^2}{2} \\ & V_c=\sqrt{\frac{u^2+v^2}{2}} \end{aligned} $

Asked in: JEE Main 2012 (19 May Online)

Practice more Motion In One Dimension questions on Aicharya