The velocity -time graph of a ball of mass 20 g moving along a straight line on a long table is given in

How much force does the table exert on the ball to bring it to rest?

Explanation

The initial velocity of the ball is 20 cm `s^(-1)`. Due to the friction force exerted by the table, the velocity of the ball decreases down to zero in 10 s. Thus, u = 20 cm `S^( -1)`, -Ocm `s^(-1)` " and t = 10 s. Since the velocity-time graph is a straight line. It is clear that the ball moves with a constant acceleration. The acceleration a is
`a=(v-u)/(t)`
=-2 cm `s^(-2)` The force exerted on the ball F is
F=ma
`=((20)/(1000))kg xx(-0.02 m s^(-2))` The negative sign implies that the frictional force exerted by the table is opposite to the direction of motion of the ball.