A highly elastic ball moving at a speed of 3 m / s approaches a wall moving towards it with a speed of 3 m / s. After the collision, the speed of the ball will be

Question

A highly elastic ball moving at a speed of 3 m / s approaches a wall moving towards it with a speed of 3 m / s. After the collision, the speed of the ball will be (A) 3 m / s (B) 6 m / s (C) 9 m / s (D) zero

Tardigrade Admin · Accepted Answer

For elastic collision, e=1. Let speed of the ball be v towards left after collision, then w.r.t wall, incident velocity = reflected velocity. We get 3+3=v-3 ⇒ v=9 m / s.

Q. A highly elastic ball moving at a speed of $3 m / s$ approaches a wall moving towards it with a speed of $3 m / s$ . After the collision, the speed of the ball will be

$3 m / s$

$6 m / s$

$9 m / s$

zero

For elastic collision, $e = 1$ .
Let speed of the ball be $v$ towards left after collision,
then w.r.t wall, incident velocity $=$ reflected velocity.
We get $3 + 3 = v - 3$
$\Rightarrow v = 9 m / s$ .

Q. A highly elastic ball moving at a speed of 3m/s approaches a wall moving towards it with a speed of 3m/s. After the collision, the speed of the ball will be

3m/s

6m/s

9m/s