How many significant forces act on a book at rest on a table? Identify the forces.
Solution Step 1 of 2 Normal force is the contact force , which exists between the contact surfaces. It acts perpendicular to the contact surface. (due to action reaction pair). Weight is due to the gravitational of the earth, which is exerted on the object with mass m on the earth surface. It acts always towards the earth. That is W= mg Where m is the mass of the object and g is acceleration due to gravity.