Wheels

The wheel is a device that enables efficient movement of an object across a surface where there is a constraint pressing the object to the surface

Hackneyed examples are a visit cart drawn by a horse, and the rollers on an aircraft flap mechanism.

The depressed resistance to motion (compared to dragging) is explained as follows (refer to friction): If dragging a 100 kg substance for 10 m along a surface with μ = 0.5, the normal force is 981 N and the work done (required energy) is (work=force x distance) 981 × 0.5 × 10 = 4905 joules.