Q. The driver of an express train moving with a velocity $v_{1}$ finds that a goods train is moving with a velocity $v_{2}$ in the same direction on the same track. He applies the brakes and produces a retardation $a$. The minimum time required to avoid collision is
A) $\frac{v_{1} - v_{2}}{a}$
B) $\frac{v_{1}}{a}$
C) $\frac{v_{2}}{a}$
D) $\frac{v_{1} + v_{2}}{a}$
Explanation
(a) $v_{1} - v_{2} = at$
or $t = \frac{v_{1} - v_{2}}{a}$.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.