A train of length l, traveling at a constant velocity, passes a pole in t seconds. If the same train
traveling at the same velocity passes a platform in 3t seconds, then the length of the platform is
(A) 0.5l
(B) l
(C) 1.5l
(D) 2l
(E) 3l
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4 comments:
explain
explain buddies....
D - If it takes t secs to pass l length of train and if takes 3t secs to pass l lenght of train.. it means that the length of platform is 2l...
i.e. 2l(platform)+l(train length) = 3t secs.
hope it is correct. scrap me if anything wrong
The distance traveled by the train while passing the pole is l (which is the length of the train). The
train takes t seconds to pass the pole. Recall the formula velocity = distance/time. Applying this formula,
we get
velocity =l/t
While passing the platform, the train travels a distance of l + x, where x is the length of the platform. The
train takes 3t seconds at the velocity of l/t to cross the platform. Recalling the formula distance =
velocity × time and substituting the values for the respective variables, we get
[l + x] =[l/t]× 3t
by substitution
l + x = 3l by canceling t
x = 2l by subtracting l from both sides
Hence, the length of the platform is 2l. The answer is (D).
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