Question

A ball of mass 10 kg is moving with a velocity of 10 m/s. It strikes another ball of mass 5 kg which is moving in the same direction with a velocity of 4 m/s. If the collision is elastic, their velocities after the collision will be, respectively

• A. 6 m/s, 12 m/s
• B. 12 m/s, 6 m/s
• C. 12 m/s, 10 m/s
• D. 12 m/s, 25 m/s

Answer 1

Answer: (A)

6 m/s, 12 m/s

Answer 2

$v _ { 1 } = \left( \frac { m _ { 1 } - m _ { 2 } } { m _ { 1 } + m _ { 2 } } \right) u _ { 1 } + \left( \frac { 2 m _ { 2 } } { m _ { 1 } + m _ { 2 } } \right) u _ { 2 }$ and

$v _ { 2 } = \left( \frac { 2 m _ { 1 } } { m _ { 1 } + m _ { 2 } } \right) u _ { 1 } + \left( \frac { m _ { 1 } - m _ { 2 } } { m _ { 1 } + m _ { 2 } } \right) u _ { 2 }$

on putting the values and $v _ { 2 } = 12 \mathrm {~m} / \mathrm { s }$