Question

A cart is coasting at a speed v A along a straight and level road. When ten percent of the
wagon’s mass is thrown off the wagon, parallel to the ground, and in the forward direction, the
wagon stops. However, if this same amount of mass is thrown out the back of the wagon, at the
same relative speed as before, the wagon accelerates to a new speed v B . Calculate the ratio v B /v A .

Answer 1

conservation of momentum
a) mVa=.9m*0+.1m*'v

throwing speed=mVa/.1m=10Va

b) mVa=.9m*Vb-.1m(10Va)
calculate Vb/Va

Answer 2

20/9