Question

Train A crosses train B, which is stationary, in 90 seconds. After a few minutes, train B travels at a uniform speed and crosses train C, running at twice the speed in the opposite direction, in 30 seconds. If the trains are of equal length, what is the ratio of their speeds?​

Answer 1

Given : Train A crosses train B, which is stationary, in 90 seconds.

Train B travels at a uniform speed and crosses train C  running at twice the speed in the opposite direction, in 30 seconds.

the trains are of equal length,

To Find : what is the ratio of their speeds?​

Solution:

Let say length of Each train = L m

Train A crosses train B, which is stationary, in 90 seconds.

Distance covered by Train A = 2L  m

Speed of Train A = 2L/90    = L/45  m/s

train B travels at a uniform speed and crosses train C

running at twice the speed in the opposite direction, in 30 seconds.

Speed of train B  =  B    Speed of Train C  = 2B

Relative speed =  B + 2B  = 3B

Distance Covered  = 2 L  m

Time 30 Sec

=> 3B  = 2L/30

=> B = L/45

Speed of Train A =  L/45  m/s

Speed of Train  B  =   L/45  m/s

Speed of Train  C =   2L/45  m/s

Ratio of Speeds of Train A , B &  C are = 1  : 1 : 2

Learn More:

A driver of train A moving at a speed 30 m/s sights another train B ...

https://brainly.in/question/11911821

The ratio of the speed of two trains A and B running in the opposite ...

https://brainly.in/question/23295098