AP EAMCET20224 Jul 2022Evening ShiftPhysicsCenter of Mass, Momentum and CollisionActual
Two balls A and B , of masses M and 2 M respectively collide each other. If the ball A moves with a speed of 150 m s - 1 and collides with ball B moving with speed v in the opposite direction. After collision if ball A comes to rest and the coefficient of restitution is 1 (one), then the speed of the ball B before it collides with ball A is
Options
- A37 . 5   m   s - 1
- B12 . 5   m   s - 1
- C75   m   s - 1
- D25   m   s - 1
Correct answer
A. 37 . 5   m   s - 1
Step-by-step solution
Applying conservation of linear momentum before and after collsion, M 150 + 2 M v = M 0 + 2 M v ' ⇒ 150 + 2 v = 2 v '         ⇒ v ' = 75 + v           . . . . 1 Now, coefficient of restitution is given by e = v ' - 0 150 - v = 1 ⇒ 150 - v = v '             . . . 2 From equation 1 and 2 , we have 150 - v = 75 + v ⇒ 75 = 2 v ⇒ v = 37 . 5   m   s - 1 Thus, speed of ball B before it collides with ball A is