What force causes a mousetrap car to stop?
Friction force if the surface is level. Friction between the wheel hubs and the axles, and friction between the wheel rims and surface, and air friction to a lesser extent, which we call drag. Friction and gravity if the surface is inclined. As the car goes up hill, it will convert kinetic energy into potential energy by working against the force of gravity. This is in addition to all the friction forces listed earlier…they’re still there on a slanted surface. And there is always the possiblity of impact force, if the car runs into a wall or other object. In which case we’d have F = dP/dT; where dP is a change in momentum over some interval of time dT, as an additional force to gravity and friction.
