14
Q:

# Two trains started at the same time, one from A to B and the other from B to A . If they arrived at B and A respectively 4 hours and 9 hours after they passed each other the ratio of the speeds of the two trains was

 A) 2:1 B) 3:2 C) 4:3 D) 5:4

Explanation:

Note : 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)

Therefore, Ratio of the speeds of two trains = $\inline \sqrt{9}:\sqrt{4}$ = 3 : 2

Q:

The length of two superfast trains are 140 mts and 160 mts respectively. If they run at the speed of 60 km/hr and 80 km/hr respectively in opposite direction, find the time in which they will cross each other ?

 A) 7.71 sec B) 10.48 sec C) 9.36 sec D) 8.45 sec

Explanation:

Given L1 = 140 m

L2 = 160 m

S1 = 60 km/hr

S2 = 80 km/hr

From the question we get,

S1 + S2 = (L1 + L2) / T

=> (60 + 80) 5/18 m/s = 140 + 160/T

=> T = 54/7 = 7.71 sec

5 99
Q:

A passenger train is moving at a speed of 120 km/hr. If the length of the train is 101 meters, how long will it take to cross a railway platform 154 meters long ?

 A) 6.24 sec B) 6.58 sec C) 7.325 sec D) 7.65 sec

Explanation:

Here total distance = 154 + 101 = 255 mts
Given speed = 120 kmph = 120x5/18 m/sec
Hence, Time = d/s = 255x18/120x5 = 7.65 sec

4 150
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.

3 200
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.

2 166
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.