Velocity versus time graph of a ball of mass `50g` rolling on a concrete floor shown in (figure) Calcualte the acceleration and frictional force of the floor on the ball.

Explanation

Given, mass `m=50g=(50)/(1000)=0.05kg`
Initital velocity, `u=80ms^(-1)`
final velocitym v=`0ms^(-1)`
Time taken, t=8s
From first equation of motion v=u+at
at=u-v
`"Aceleration",a=(v-u)/(t)=(0-80)/(8)=(-80)/(8)=-10ms^(-2)`
Now, frictionless force of the floor on the ball,
`F=ma=0.05xx-10=-0.5N` (Negative sign shown the direction of motion)