A passenger train is traveling at 29 m/s when the engineer sees a freight train 360m ahead traveling on the same track in the same direction. The freight train is moving at 6 m/s. If the reaction time of the engineer is .4s, what must be the deceleration of the passenger train if a collision is to be avoided?
If someone can help me with this I would greatly appreciate it!
2007-09-23 13:15:21 · 1 answers · asked by kathleen 1 in Science & Mathematics ➔ Physics
This is easier if you choose the right reference system. Ignore the ground. Consider only the front of the fast train and the rear of the slow one. The passenger train is approaching a freight train at a relative speed of 23 m/s.
So the passenger has to slow to 0 m/s (with respect to the rear of the freight).
Use
Vf^2 = Vo^2 +2*a*x
where Vf = 0 m/s, Vo = 23 m/s, and x is the distance between them after the engineer's reaction time (which would be
360 m - (23 m/s)*0.4 s).
2007-09-23 14:04:56 · answer #1 · answered by sojsail 7 · 0⤊ 0⤋