Question

two trains Aand B of lengh 400m each are moving on two parallel tracks at speed of 72 km/h and 54km/h respectively in opposite directions in what time a) they will cross each other b) they will overtake ​

Answer 1

Answer:

ANSWER

For train A:

Initial velocity, u = 72 km/h = 20 m/s

Time, t = 50 s

Acceleration, aI = 0 (Since it is moving with a uniform velocity)

From second equation of motion, distance (sI)covered by train A can be obtained as:

s = ut + (1/2)at2= 20× 50 + 0 = 1000 m

For train B:

Initial velocity, u = 72 km/h = 20 m/s

Acceleration, a = 1 m/s2

Time, t = 50 s

From second equation of motion, distance (sII) covered by train A can be obtained as:

s II = ut + (1/2)at

2= 20 X 50 + (1/2) 1 (50) = 2250 m

Hence, the original distance between the driver of train A and the guard of train B is 2250 - 1000 = 1250m.