# physics

posted by
**ben**
.

A red train traveling at 72 km/h and a green train traveling at 144 km/h are headed toward one another along a straight, level track. When they are 950m apart, each engineer sees the otherâ€™s train and applies the brakes. The brakes decelerate each train at the rate of 1 m/s^2. Is there a collision? If so what is the speed of each train at impact? If not what is the separation between the trains when they stop?

I will be happy to critique this for you. Hint: The distance the slower train travels is 1/2 the faster train. So see if the slow train can stop in 950(2/3) m.

Vf^2= vo^2 - 2ad

change Vo to m/s If you get a solution here with vf=0 for d less than 2/3 950, then they do not collide.

I got d as 800m for the faster train. so they do collide. To find the speed of the each train what would I have to do?