20. The driver of a train, travelling at 115 km/hr, sees aslow train t

1.	20. The driver of a train, travelling at 115 km/hr, sees aslow train travelling on the same track, which is100 m infront of him and in the same direction at aspeed of 25 km/hr. The least retardation that must beapplied to faster train to avoid a collision is(1) 5 m/s2(3) 3.125 m/s (4) 7 m/s(2) 2.5 m/s
Answer» Velocity of train 'B' with respect to train 'A' = (115−25)km/h VBA=−90km/h =−25m/s Distance between the trains is 100m. Using the equations of motion v^2=u^2−2as ,v=0 u^2=2as 625=2xax100 Then the least retardation that must be appiled to faster train to avoid a collision, a=3.125m/s^2

20. The driver of a train, travelling at 115 km/hr, sees aslow train travelling on the same track, which is100 m infront of him and in the same direction at aspeed of 25 km/hr. The least retardation that must beapplied to faster train to avoid a collision is(1) 5 m/s2(3) 3.125 m/s (4) 7 m/s(2) 2.5 m/s

Answer»

Velocity of train 'B' with respect to train 'A' = (115−25)km/h

VBA=−90km/h =−25m/s

Distance between the trains is 100m. Using the equations of motion

v^2=u^2−2as ,v=0

u^2=2as

625=2xax100

Then the least retardation that must be appiled to faster train to avoid a collision, a=3.125m/s^2

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