A box of mass M rests on a smooth floor. A small block of mass m inside it is given speed v₀ relative to the floor and repeatedly bounces between the walls. When the block finally comes to rest relative to the box, the final speed of the box is:

Question

A box of mass M rests on a smooth floor. A small block of mass m inside it is given speed v₀ relative to the floor and repeatedly bounces between the walls. When the block finally comes to rest relative to the box, the final speed of the box is:

G1 Physics · Accepted Answer

Use p = mv and conservation of total linear momentum for an isolated system. Resolving components with the given data gives D: [m/(m+M)]v₀.