Statics Example A running car a braking car The back wheel has driving moment. The back wheel has no driving moment If the back wheel leaves the ground If the back wheel leaves the ground the direction of motion is backward. the direction of motion is forward 77 [Example] The back wheel has driving moment. The back wheel has no driving moment. If the back wheel leaves the ground If the back wheel leaves the ground the direction of motion is backward. the direction of motion is forward. A running car A braking car