Two trains, one 160 m and the other 140 m long are running in opposite directions on parallel tracks, the first at 77 km an hour and the other at 67 km an hour. How long will they take to cross each other ?
A. 7 sec
B. $$7\frac{1}{2}$$ sec
C. 6 sec
D. 10 sec
Answer: Option B
Solution(By Examveda Team)
$$\eqalign{ & {{\text{V}}_{{\text{rel}}{\text{.}}}} = 77 + 67 = 144{\text{ km/hr}} \cr & {\text{ = 144}} \times \frac{5}{{18}}{\text{ m/sec}} \cr & = 40{\text{ m/sec}} \cr & \therefore {\text{ T}} = \frac{{\text{D}}}{{{{\text{V}}_{{\text{rel}}{\text{.}}}}}} \cr & \Rightarrow {\text{T}} = \frac{{140 + 160}}{{40}} \cr & \Rightarrow {\text{T}} = \frac{{300}}{{40}} \cr & \Rightarrow {\text{T}} = 7.5\sec {\text{or 7}}\frac{1}{2}\,\sec \cr} $$Related Questions on Speed Time and Distance
A. 48 min.
B. 60 min.
C. 42 min.
D. 62 min.
E. 66 min.
A. 262.4 km
B. 260 km
C. 283.33 km
D. 275 km
E. None of these
A. 4 hours
B. 4 hours 30 min.
C. 4 hours 45 min.
D. 5 hours
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