99 Percentile Qs Bank for JEE MainPhysicsCenter of Mass, Momentum and Collision
A smooth steel ball strikes a fixed smooth steel plate at an angle θ with the vertical. If the coefficient of restitution is e , the angle at which the re-bounce will take place is
Options
- Aθ
- Btan - 1 tan θ e
- Ce tan θ
- Dtan - 1 e tan θ
Correct answer
B. tan - 1 tan θ e
Step-by-step solution
Since, no force is present along the surface of plate. So, momentum conservation principle for ball is applicable along the surface of plate. m υ sin θ 1 = m υ sin θ 2 Or υ sin θ 1 = υ 1 sin θ 2 …(i) e = υ 1 cos θ 2 υ cos θ 1 = υ 1 cos θ 2 υ cos θ ( θ 1 = θ ) ∴ υ 1 cos θ 2 = e υ cos θ …(ii) ∴ υ 1 sin θ 2 υ 1 cos θ 2 = υ sin θ e υ cos θ = tan θ e ∴ tan θ 2 = tan θ e ∴ θ 2 = tan - 1 tan θ e