Awoman exerts a constant horizontal force on a large box. as a result, the box moves across a horizontal floor at a constant speed "vo". if the woman suddenly stops applying a horizontal force to the block, then the block will

The woman is exerting a constant horizontal force on the box, yet it is moving across the floor at a constant speed. That means there is a frictional force on the box equal in magnitude to the applied force and opposite in direction. When the woman stops applying this force, the box will still be subject to the frictional force. It will then decelerate until it stops moving.

e/c, where e is its total energy