Question

A massive ball moving with speed v collides head-on with a tiny ball at rest having a very small mass as compared to the first ball. If the collision is elastic, then immediately after the impact, the second ball will move with a speed approximately equal to

• A. v
• B. 2v
• C. v/2
• D. $\infty$

Answer 1

The correct option is B 2v

$m_1>>m_2$ ; velocity df massive ball$=$v
In a head-on elastic collision where the projectile is much more massive than the target, the velocity of the target particle after the collision will be about twice that of the projectile and the projectile velocity will be essentially unchanged. So, the second ball will move with a speed approximately equal to 2v.