Rolling resistance, sometimes called
rolling friction or
rolling drag, is the force resisting the
motion when a body (such as a
ball,
tire, or
wheel) rolls on a surface. It is mainly caused by
non-elastic effects; that is, not all the energy needed for deformation (or movement) of the wheel, roadbed, etc. is recovered when the pressure is removed. Two forms of this are hysteresis losses (see below), and permanent
(plastic) deformation of the object or the surface (e.g. soil). Another cause of rolling resistance lies in the
slippage between the wheel and the surface, which dissipates energy. Note that only the last of these effects involves
friction, therefore the name "rolling friction" is to an extent a misnomer.