On: Japan maglev train breaks world speed record again

[Retric]

The bottom of a wheel is stationary relative to the ground. (X - X)

The middle a the wheel moves at the same speed as the vehicle relative to the ground. (X + 0)

The top of the wheel moves at twice the speed of the vechile relative to the ground. (X + X)

Put another way, the top of the wheel must go faster than the vehicle or it does not rotate.