A bullet mass = m) is fired at speed V into a block of mass M with M m) which is hanging vertically from a light string of length L. The bullet stops in the block. If the recoiling block + bullet system reaches a height of 2/3L, then the initial speed of the bullet is given by A) M  1gL/3)^1/2/m. B) M  2gL/3)^1/2/m. C) M  3gL/4)^1/2/m. D) m  4gL/3)^1/2/M. E) M  4gL/3)^1/2/m.

Question

A bullet mass = m) is fired at speed V into a block of mass M with M > m) which is hanging vertically from a light string of length L. The bullet stops in the block. If the recoiling block + bullet system reaches a height of 2/3L, then the initial speed of the bullet is given by A) M  1gL/3)^1/2/m. B) M  2gL/3)^1/2/m. C) M  3gL/4)^1/2/m. D) m  4gL/3)^1/2/M. E) M  4gL/3)^1/2/m.

Quizplus · Accepted Answer

The conservation of momentum and energy principles are used. The initial kinetic energy of the bullet is converted into potential energy at the maximum height. Solving for the initial speed gives the expression in choice E.

A Bullet Mass = M) Is Fired at Speed V