Q. Two trains travelling on the same track are approaching each other with equal speeds of 40$m/s$. The drivers of the trains begin to decelerate simultaneously when they are just $2.0km$ apart. Assuming the decelerations to be uniform and equal, the value of the deceleration to barely avoid collision should be
A) $11.8\ m/s^{2}$
B) $11.0\ m/s^{2}$
C) $2.1\ m/s^{2}$
D) $0.8\ m/s^{2}$
Explanation
(d) Both trains will travel a distance of $1\ km\ $before to come in rest. In this case by using $v^{2} = u^{2} + 2as$
$\Rightarrow 0 = (40)^{2} + 2a \times 1000 \Rightarrow a = - 0.8\ m/s^{2}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.