Q. A car moving with speed of $40\ km/h$ can be stopped by applying brakes after atleast $2\ m$. If the same car is moving with a speed of $80\ km/h$, what is the minimum stopping distance
A) $8\ m$
B) $2\ m$
C) $4\ m$
D) $6\ m$
Explanation
(a) $S \propto u^{2}\ \therefore\frac{S_{1}}{S_{2}} = \left( \frac{u_{1}}{u_{2}} \right)^{2} \Rightarrow \frac{2}{S_{2}} = \frac{1}{4} \Rightarrow S_{2} = 8\ m$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.