Physics help!- two trains approach..

Physics
Tutor: None Selected Time limit: 1 Day

Two trains approach each other on a straight track. the first is moving to the right at 12 m/s the second train is coming up behind it at 25 m/s. when the second train is 200 m behind the first, the engineer applies the brakes, causing the train to deacellerate at 0.2 m/s2. will the trains collide? if so, how long after the brakes were applied?

Sep 14th, 2015

Thank you for the opportunity to help you with your question!

time to decelerate

vi =-at

25m/s =-0.2m/s * t

t =25m/s/0.2= 125s

distance covered will be = vi*t +1/2 at2

=25m/s*125 +1/2*-0.2*125^2= 3125-1562.5 = 1562.5m

distance covered by train moving at 12m/s in 125 sec

d=125*12 = 1500m 

toal distance = 1500+200 =1700. trains will not collide 

Please let me know if you need any clarification. I'm always happy to answer your questions.
Sep 14th, 2015

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