Question

A 20N stone rests on a table. What is the force the table exerts on the stone? In what direction?

Answer 1

Answer: The force exerted by table on the stone will be 20 N in upward direction.

Explanation:

Balanced forces are defined as the forces which gets cancelled out when equal forces are acting in the opposite direction. The net force on the system comes out to be 0.

Unbalanced forces are defined as the forces which does not get cancelled out because unequal forces act on the system in opposite direction. The motion of the object is in the direction of net force.

According to the question:

The force exerted by the stone on the table in downward direction = 20 N

Net force acting on the stone = 0 N (because it is at rest)

So, the force exerted by the table on the stone will be same, which is equal to 20 N but in upward direction.

Hence, the force exerted by the table on the stone is 20 N in upward direction.

Answer 2

Stone exerts force on table and in reaction table exerts force called "Normal Reaction" on stone in upward direction. Due to which it does not fall. Friction also causes stone to be in rest.