The velocity versus time graph of a ball of mass $50 \, g$ rolling on a concrete floor is shown in the figure. Calculate the acceleration and the frictional force exerted by the floor on the ball.

(N/A) Given:
Mass of the ball,$m = 50 \, g = 0.05 \, kg$
Initial velocity,$u = 80 \, m \, s^{-1}$ (at $t = 0 \, s$)
Final velocity,$v = 0 \, m \, s^{-1}$ (at $t = 8 \, s$)
Time taken,$t = 8 \, s$
$1$. Calculation of acceleration $(a)$:
$a = \frac{v - u}{t} = \frac{0 - 80 \, m \, s^{-1}}{8 \, s} = -10 \, m \, s^{-2}$
The negative sign indicates retardation (deceleration).
$2$. Calculation of frictional force $(F)$:
$F = m \times a$
$F = 0.05 \, kg \times (-10 \, m \, s^{-2}) = -0.5 \, N$
The negative sign indicates that the frictional force acts in the direction opposite to the motion of the ball.