As shown in the figure, ABC is a smooth track, in which the BC part is a vertically placed semi-circular track with a radius of R, and a small wooden block with a mass of m is placed in the horizontal

As shown in the figure, ABC is a smooth track, in which the BC part is a vertically placed semi-circular track with a radius of R, and a small wooden block with a mass of m is placed in the horizontal part of the track. Solution: Solution:

(1) When the block reaches point C, the centripetal force is provided by the combined force of gravity and orbital elasticity, which is obtained according to Newton's second law.

(M+m)g+N=(M+m)v2CR

Solve? vc=2gR

(2) According to the law of conservation of momentum, the process of bullets entering the wood block is obtained.

mv0=(M+m)v

The community process from B to C is derived from the law of conservation of mechanical energy.

12(M+m)v2=(M+m)g？ 2R+ 12(M+m)v2C

Again? vc=2gR

Simultaneous solution

v0=M+mm6gR

Answer: (1) The speed of the box at point C is 2gR. ..

(2) Before entering the wood block, the velocity of the bullet is v0 = m+mm6gr.