Two trains- one travelling at 72km/hr and other at 90km/hr are heading towards one another along a straight level track. When they are 1.0 km apart, both the drivers simultaneouly see the each other's train and apply brakes which retard each train at the rate of 1.0m/s*2. Determine whether the trains would collide or not and at what distance the train will stop after the brakes are apllied?

Suppose the distance travelled by both the trains before they stop =sFor train 1,u=72 km/h=72×10001×60×60m/s=20 m/sa=-1m/s2Using relation,v2-u2=2as0-202=2×(-1)×s400=2ss=200 mFor train 2,u=90 km/h=90×10001×60×60=25 m/sa=-1m/s2v2-u2=2as0-252=2×(-1)×ss=312.5 m
Since they are 1 km i.e. 1000 m apart and sum of both their distance is less than 1000 m, they would stop before time.
There would no collision.

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