On a velocity - time graph, if the line crosses the x - axis it depicts that the object has started moving in the opposite direction.
Answer:

Explanation:
If the object is rolling without slipping, every unit of rotated angle equals to a distance perimeter rotated.
Suppose the object complete 1 revolution within time t. The angular distance is 2π rad. Its angular velocity is 2π/t
The distance it covered is its circumference, which is 2πr, and so the speed is 2πr/t
So the linear speed compared to angular speed is


D. Equal to zero.
Because the forces balance each other.