Demonstration Maxwell's wheel (explained)

Maxwell's wheel is the classic way of showing the interplay between potential energy and kinetic energy, along with the effects of nearly-elastic collisions. Maxwell's wheel consists of an axle-mounted flywheel suspended by nylon cords at both ends. Wind it up to the top of the frame and let it go!
As it drops, gravitational potential energy changes to the kinetic energy of the wheel's descent and rotation.
The jerk when the wheel reaches the bottom reverses the linear momentum causing the wheel to wind back up.
A small amount of energy is lost each time due to the friction of the nearly-elastic collision that occurs when the wheel jerks at the bottom. When it has unwound to the bottom, the sharp jerk on reaching the end of the nylon cords reverses its linear momentum (while maintaining its angular momentum). This "collision" at the bottom is nearly elastic - some of the kinetic energy is lost. The ratio of energy kept to starting energy tells you how "elastic" the collision was through its coefficient of restitution.