Q. 204.2( 5 Votes )

# Two trains A and B of length 400 m each are moving on two parallel tracks with uniform speed of 72 kmh^{-1} in the same direction with A ahead of B. The driver of B decides to overtake Aand accelerate by 1 ms^{-2}. If after 50 s, the guard of B just passes the driver of A, what was the original distance between them?

Answer :

**Train A**

Initial Velocity = U_{A} = 72 kmh^{-1} = 20 ms^{-1}

Time Taken = t = 50s

Acceleration = a_{A} = 0 ms^{-2}

Now, from the equations of motion, we know that,

m

Driver is at starting of Train A

**Train B**

Initial Velocity = U_{A} = 72 kmh^{-1} = 20 ms^{-1} Time Taken = t = 50 s

Acceleration = a_{B} = 1 ms^{-2}

Now, from the equations of motion, we know that,

m

Guard is at the end of Train B

Now, length of both trains = 400 m + 400 m = 800 m

Now, Original distance between Train A and B is S, which can be obtained as given below:

S = 2250 m – 1000 m – 800 m

= 450 m

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