13
Q:

# Two trains of equal length , running in opposite directions , pass a pole in 18 and 12 seconds. The trains will cross each other in

 A) 14.4 sec B) 15.5 sec C) 18.8 sec D) 20.2 sec

Explanation:

Let the length of the train be L metres

Speed of first train = $\inline&space;\frac{3600}{18}\times&space;L$ m/hour

Speed of secxond train = $\inline&space;\frac{3600}{12}\times&space;L$ m/hour

When running in opposite directions, relative speed = 200 L + 300 L m/hour

Distance to be covered = L + L = 2L metre

Time taken = $\inline&space;\frac{2L}{500L}\times&space;3600$ sec

=14.4 sec

Q:

A 260 m long train running at the speed of 120 km/hr crosses another train running in opposite direction at the speed of 80 km/hr in 9 sec. What is the length of the other train  ?

 A) 240 mts B) 270 mts C) 260 mts D) 250 mts

Explanation:

Relative speed = 120 + 80 = 200 km/hr.
= 200 x 5/18 = 500/9 m/sec.

Let the length of the other train be L mts.
Then, (L + 260)/9 = 500/9 => L = 240 mts.

3 19
Q:

A train 125 m long passes a man, running at 4 km/hr in the same direction in which the train is going, in 10 seconds. The speed of the train is:

 A) 49 kmph B) 50 kmph C) 51 kmph D) 52 kmph

Explanation:

Speed of the train relative to man

= (125/10) m/sec = (25/2) m/sec.

[(25/2) x (18/5)] km/hr = 45 km/hr.

Let the speed of the train be 'x' km/hr.

Then, relative speed = (x - 4) km/hr.

x - 4 = 45 => x = 49 km/hr.

2 16
Q:

Two trains are moving in opposite directions at 60 km/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 ?

 A) 42 sec B) 44 sec C) 46 sec D) 48 sec

Explanation:

Relative speed = 60 + 90 = 150 km/hr.

= 150 x 5/18 = 125/3 m/sec.

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

Required time = 2000 x 3/125 = 48 sec.

1 30
Q:

Two trains are moving in the same direction at 72 kmph and 36 kmph. The faster train crosses a girl sitting at window seat in the slower train in 32 seconds. Find the length of the faster train ?

 A) 170 m B) 100 m C) 270 m D) 320 m

Explanation:

Relative speed = (72 - 36) x 5/18 = 2 x 5 = 10 mps.
Distance covered in 32 sec = 32 x 10 = 320 m.

The length of the faster train = 320 m.

1 49
Q:

Train X crosses a stationary train Y in 60 seconds and a pole in 25 seconds with the same speed. The length of the train X is 300 m. What is the length of the stationary train Y ?

 A) 360 m B) 420 m C) 460 m D) 320 m

Explanation:

Let the length of the stationary train Y be LY
Given that length of train X, LX = 300 m
Let the speed of Train X be V.
Since the train X crosses train Y and a pole in 60 seconds and 25 seconds respectively.
=> 300/V = 25 ---> ( 1 )
(300 + LY) / V = 60 ---> ( 2 )
From (1) V = 300/25 = 12 m/sec.
From (2) (300 + LY)/12 = 60
=> 300 + LY = 60 (12) = 720
=> LY = 720 - 300 = 420 m
Length of the stationary train = 420 m