Given,Â
Radius of the wheel = RÂ
When half revolution is made by the wheel, the point of contact moves from point A to C and hence undegoes the displacement Â
Distance displaced by the point of contact, AB = Â
Perpendicular distance traversed by the body = 2R
Therefore, total distance,Â
and Â
Thus the point of contact undergoes the displacement of magnitude  making an angle  with the ground.
A river d km wide is flowing at a rate  A swimmer which can swim with velocity  relative to water, dives into the river perpendicular to the direction of flow to cross the river. How far he will go down the river along the river?