# Homework Help: Train collision

1. Jan 22, 2010

### ts21121

A passenger train is traveling at 30 m/s when the engineer sees a freight train 336 m ahead of his train traveling in the same direction on the same track. The freight train is moving at a speed of 5.9 m/s.

1.If the reaction time of the engineer is 0.36 s, what is the minimum (constant) rate at which the passenger train must lose speed if a collision is to be avoided?

2. If the engineer's reaction time is 0.79 s and the train loses speed at the minimum rate described in Part (a), at what rate is the passenger train approaching the freight train when the two collide?

For both reaction times, how far will the passenger train have traveled in the time between the sighting of the freight train and the collision?

x=x0+v0t +1/2 at2
v=v0+at

3. The attempt at a solution
for part 1 i know the answer is .887m/s^2.
after this i am completely lost on how to solve for part 2 and 3
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Jan 22, 2010

### rl.bhat

Hi ts21121, welcome to PF.
I am getting slightly different answer for the part 1. Will you show your calculations?