The momentum conservation of the system takes the initial velocity direction of the wooden box as the positive direction, which is obtained by the law of momentum conservation:
(M+m)v0=mv+MvA 1？ ①
The monkey jumped into the wooden box B, and then jumped out of the wooden box B. The momentum of the system composed of B and the monkey is conserved, and the initial velocity direction of the monkey is positive.
From the law of conservation of momentum: mv = mv+mvb2, the solution is: vB=0? ④
When wooden box A catches up with wooden box B, there is a direct collision, and the momentum of AB system is conserved.
Taking the initial velocity direction of a as the positive direction, it is obtained by the law of conservation of momentum:
MvA 1=2MvAB ⑤ Solution: vAB=0.75m/s, and the direction is horizontal to the right ⑤.
When the monkey jumps into the wooden box C, the momentum is conserved, and the speed direction of the monkey is positive.
According to the law of conservation of momentum, mv=(m+M)vC⑦.
Solution: vC=2m/s, and the direction is horizontal to the right? ⑧;
A: The final speed of wooden cases A and B is 0.75m/s, and the direction is right. The final speed of the wooden box C is 2m/s, and the direction is right.