# A wheel of radius 1 meter rolls forward half a revolution on a horizontal ground. The magnitude of the displacement of the point of the wheel initially in contact with the ground is ?

The word "initially" is important here. If we were examining the point of the wheel in contact with the ground, the displacement would be zero. Instead, we are looking at how far (straight) a point has moved after a $\pi$ radians revolution.
At half a circumference of travel, the displacement is $2 r$ upwards.
$D = 2 \left(1\right) = 2 \text{m}$