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

The Correct Option is A

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