The speed time graph of a ball of mass `30g` moving along a straight line is shown in (figure). Calculate the opposing force that brings the ball to rest.

Explanation

Here `m=30g= 0.03kg, F=?`
From the graph, we find `u=50m//s, v=0, t=4 s`
As `v=u+at`
`:. 0=50+axx4, a=(-50)/4= -12.5m//s^(2)`
`F=ma= 0.03xx(-12.5)= -0.37N`
Negative sign is for opposing force of friction.