Question

The driver of a car travelling at velocity $v$ suddenly sees a broad wall in front of him at a distance $d$. He should

• A. brake sharply
• B. turn sharply
• C. (a) and (b) both
• D. none of the above

Answer 1

Answer: (A)

brake sharply

Answer 2

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, $\frac{1}{2}mv^2=Fx$ $\Rightarrow x=\frac{mv^2}{2F}$ But when the makes turn, then $\frac{mv^2}{r}=F$ $\Rightarrow r=\frac{mv^2}{F}$ It is clear that.v = $\frac{r}{2}i,e,$ 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