Kinematics Question 162
Question: A train is moving at a constant speed V when it’s driver observes another train in front of him on the same track and moving in the same direction with constant speed v. If the distance between the trains it’s x, then what should be the minimum retardation of the train so as to avoid coll it’sion?
Options:
A) $ \frac{(V+v) _{{}}^{2}}{x} $
B) $ \frac{(V-v) _{{}}^{2}}{x} $
C) $ \frac{(V+v) _{{}}^{2}}{2x} $
D) $ \frac{(V-v) _{{}}^{2}}{2x} $
Show Answer
Answer:
Correct Answer: D
Solution:
[d] Here relative velocity of the train W.r.t other train it’s $ V-v. $
hence, $ 0-{{(V-v)}^{2}}=2ax $ Or $ a=-\frac{{{(V-v)}^{2}}}{2x} $
Minimum retardation = $ \frac{{{(V-v)}^{2}}}{2x} $
