Question

A ball $B_{1}$ of mass M moving northwards with velocity v collides elastically with another ball $B_{2}$ of same mass but moving eastwards with the same velocity v. Which of the following statements will be true

• A. $B_{1}$comes to rest but $B_{2}$ moves with velocity $\sqrt{2}v$
• B. $B_{1}$moves with velocity $\sqrt{2}v$ but $B_{2}$ comes to rest
• C. Both move with velocity $v/\sqrt{2}$ in north east direction
• D. $B_{1}$moves eastwards and $B_{2}$ moves north wards

Answer 1

Answer: (D)

$B_{1}$moves eastwards and $B_{2}$ moves north wards

Answer 2

Horizontal momentum and vertical momentum both should remain conserve before and after collision. This is possible only for the (4) option.