(a) Forces acting on the book before it is pushed are weight (W), normal force (N) and static friction force (Fs).
(b) The applied force causes the book to move and comes to a stop to be presence of kinetic friction force.
(c) The forces acting the book moving at a constant speed are applied force and friction force which are equal in magnitude but opposite in direction.
What are the forces acting on the book?
(a) The forces acting on the book before it is pushed include:
- Weight: The force pulling the book downwards.
- Normal Force: The force exerted by the table upward on the book.
- Static friction force: This force acts on object at rest.
(b) When the student pushes the book, an external horizontal force is applied. Initially, the book moves because of the applied force.
But due to the presence of friction acting in the opposite direction, the net force decreases over time. Eventually, when the net force becomes zero, the book stops.
(c) For the book to move at a constant speed in one direction, the net force acting on the book must be zero. This means that the applied force by the student should be balanced by opposing force, (friction force).