Ballistic PendulumHardQuestion 30523
Question
A bullet (mass m, velocity v) embeds in a wooden block (mass M) hanging from strings of length L. The block+bullet swings up to height h. The bullet's initial velocity is:
- A(m+M)/m × √(2gh)Correct
- Bm/(m+M) × √(2gh)
- C(M/m) × √(gh)
- D√(2gh)
Correct answer
(m+M)/m × √(2gh)
Explanation
Collision: mv = (m+M)v'. Then energy conservation: ½(m+M)v'² = (m+M)gh → v' = √(2gh). So v = (m+M)/m × √(2gh).