Question:
A horse continues to apply a force in order to move a cart with a constant velocity. Explain why?
Solution:
The cart will move with a constant velocity if no net external force acts on it. When horse applies a force on the cart, frictional force, also acts between the tyres of the cart and the road to oppose its motion. The cart will move with constant velocity only if the force applied by the horse is equal to the frictional force.