Velocity versus time graph of a ball of mass 50 g rolling on a concrete floor is shown in Fig. 9.1. Calculate the acceleration and frictional force of the floor on the ball.


Given, m = 50g

F =?


We know, Force = mass × acceleration


= * 10 = 0.5 N


The velocity of the ball zero time is 80ms-1. It decelerates due to the friction of the floor with itself and comes to rest after 8 seconds.


a = =


= -10m/s2


The negative sign indicates that the frictional force exerted opposes the motion of the ball. Now, using Newton’s relation,


F = m× a


= × -10


= -0.5 N


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