Question

The driver of a truck travelling with a velocity $v$ suddenly notices a brick wall in front of him at a distance $d$. It is better for him to apply brakes or to make a circular turn without applying brakes in order to just avoid crashing into the wall? Why

Answer 1

When driver will make a circular turn then force for centripetal acceleration will be given by friction which is $F_f=m{v}^2/d$ But if he applies break then according to 3rd equation of motion $v^2-u^2=2ad$ Putting $v=0$ we get $a=v^2/2d$ and force required by friction will be $F_f=m{v}^2/2d$. It means when he will apply break he will need half fricional force than taking a turn. Hence driver should apply break than taking a circular turn.