Problems on Trains - Aptitude Questions and Answers - RejinpaulPlacement

36.
Two trains 200 m and 150 m long are running on parallel rails at the rate of 40 kmph and 45 kmph respectively. In how much time will they cross each other, if they are running in the same direction?

Solution:   Relative Speed = (45 – 40) kmph = 5 kmph
= (5 * (5/18)) m/sec
=(25/18) m/sec

Total distance covered = Sum of lengths of trains = 350 m.

Time taken = (350 *( 18/25)) sec = 252 sec.
37.
Two trains 140m and 160m long run at the speed of 60 km/hr and 40 km/hr respectively in opposite directions on parallel tracks. The time (in seconds) which they take to cross each other, is: [S.S.C 2004]

Solution:   Relative speed = ( 60 + 40) km/hr =100 km/hr
= (100 * (5/18)) m/sec
= (250/9) m/sec.

Distance covered in crossing each other = (140 + 160) m = 300 m

Required time = (300 * (9/250)) sec = 54/5 sec = 10.8 sec.
38.
Two trains are moving in opposite directions @ 60km/hr and 90 km/hr. Their lengths are 1.10 km and 0.9 km respectively. The time taken by the slower train to cross the faster train in seconds is : [M.B.A 2002]

Solution:   Relative speed = (60 + 90) km/hr
= (150 * (5/18)) m/sec
= (125/3) m/sec

Distance covered = (1.10 + 0.9) km = 2 km = 2000 m.

Required time = [2000 * (3/125)] sec = 48 sec.
39.
A train 125 m long passes a man, running at 5 kmph in the same direction in which the train uis going, in 10 seconds. The speed of the train is: [A.A.O Exam 2003]

Solution:   Speed of the train relative to man = (125/10) m/sec = (25/2) m/sec
= [(25/2) * (18/5)] km/hr
= 45 km/hr.

Let the speed of the train be x kmph.

Then, relative speed = (x - 5) kmph.
x - 5 = 45
x = 50 kmph.
40.
A train 110 m long passes a man, running at 6 kmph in the direction opposite to that of the train, in 6 seconds. The speed of the train is:

Solution:   Speed of the train relative to man = (110/6) m/sec
= ((110/6) * (18/5))km/hr
= 66 km/hr

Let the speed of the train be x kmph.

Then relative speed = (x + 6) kmph
x + 6 = 66
x = 60 kmph
41.
Two goods train each 500 m long, are running in opposite directions on parallel tracks. Their speeds are 45 km/hr and 30 km/hr respectively. Find the time taken by the slower train to pass the driver of the faster one.

Solution:   Relative speed = (45 + 30) km/hr =75 km/hr
= [75 * (5/18)] m/sec
= (125/6) m/sec

Distance covered = (500 + 500) m = 1000 m.

Required time = (1000 * (6/125)) sec = 48 sec.
42.
Two trains of equal length are running on parallel lines in the same direction at 46 km/hr and 36 km/hr. The faster train passes the slower train in 36 seconds. The length of each train is: