Kinematics Question 319
Question: An express train is moving with a velocity v1. it’s driver finds another train is moving on the same track in the same direction with velocity v2. To escape coll it’sion, driver applies a retardation a on the train. the minimum time of escaping coll it’sion will be [RPET 2002]
Options:
A) $ t=\frac{v _{1}-v _{2}}{a} $
B) $ t _{1}=\frac{v _{1}^{2}-v _{2}^{2}}{2} $
C) None
D) Both
Show Answer
Answer:
Correct Answer: A
Solution:
As the trains are moving in the same direction. So the initial relative speed $ (v _{1}-v _{2}) $ and by applying retardation final relative speed becomes zero. From $ v=u-at $
therefore $ 0=(v _{1}-v _{2})-at $
therefore $ t=\frac{v _{1}-v _{2}}{a} $
