Arithmetic Aptitude :: Problems on Trains
Problems on Trains - Important Formulas
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km/hr to m/s conversion:
a km/hr = \((a \times\frac{5}{18})m/s\) -
m/s to km/hr conversion:
a m/s = \( \left( \text{ a x } \frac {18 } { 5 } \right ) \) km\hr -
Formulas for finding speed.Time and Distance
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Time taken by a train of length l metres to pass a pole or standing man or a signal post is equal to the time taken by the train to cover l metres.
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Time taken by a train of length l metres to pass a stationery object of length b metres is the time taken by the train to cover (l + b) metres.
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Suppose two trains or two objects bodies are moving in the same direction at u m/s and v m/s, where u > v, then their relative speed is = (u - v) m/s.
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Suppose two trains or two objects bodies are moving in opposite directions at u m/s and v m/s, then their relative speed is = (u + v) m/s.
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If two trains of length a metres and b metres are moving in opposite directions at u m/s and v m/s, then:
The time taken by the trains to cross each other = \(\frac{(a+b)}{(u+v)}sec\) -
If two trains of length a metres and b metres are moving in the same direction at u m/s and v m/s, then:
The time taken by the faster train to cross the slower train = \( \frac{(a+b)}{(u-v)}sec\) -
If two trains (or bodies) start at the same time from points A and B towards each other and after crossing they take a and b sec in reaching B and A respectively, then:
(A's speed) : (B's speed) = (b : a).