Question

The driver of a car suddenly sees a board wall in front of him. He should

• A. Break sharply
• B. Turn sharply
• C. Both (a) and (b)
• D. None of these

Answer 1

The correct option is A Break sharply

When driver applies brakes and the car covers distance x before coming to rest, under the effect of retarding force $F$ then from work-energy theorem,

$\frac{1}{2}m{V}^2=Fx$

$\Rightarrow x=\frac{m{v}^2}{2F}$

But when the makes turn, then

$\frac{m{v}^2}{r}=F$

$\Rightarrow r=\frac{m{v}^2}{F}$

It is clear that.$x=\frac{r}{2}$ i,e,by the same retarding force the car can be stopped in a less distance if the driver apply brakes. This retarding force is actually friction force

Hence, the driver should break sharply instead of a turn.