## Question:

A boy of weight ${ W }_{ 1 }$ walks forward over the surface of the cart of weight ${ W }_{ 2 }$ with a constant speed v relative to the cart. Determine the cart’s speed and its displacement at the moment he is about to step off. Neglect the mass of the wheels and assume the cart and boy are originally at rest. Given: ${ W }_{ 1 }$ = 100 lb , ${ W }_{ 2 }$ = 60 lb , v = 3 ft/s , d = 6 ft