Homework Help

Two trains one travelling at 20m/s and the other 40m/s are headed toward one another...

user profile pic

gretjxfj | Student, Undergraduate | (Level 1) Honors

Posted August 8, 2013 at 1:30 PM via web

dislike 1 like

Two trains one travelling at 20m/s and the other 40m/s are headed toward one another along a straight level track. When they are 105 meters apart, each engineer sees the other's train and applies the brakes. The brakes decelerate each train at a constant rate of 10 m/s^2. Will the two trains collide? Explain quantitatively.

1 Answer | Add Yours

user profile pic

justaguide | College Teacher | (Level 2) Distinguished Educator

Posted August 8, 2013 at 1:52 PM (Answer #1)

dislike 1 like

The two trains headed toward each other along a straight level track are moving at 20 m/s and 40 m/s respectively. When they are 105 m apart the engineer in each of the trains sees the other and applies the brakes that result in a deceleration of 10 m/s^2.

Use the formula v^2 - u^2 = 2*a*s to determine the distance traveled by each of the trains before they come to a stop.

For the train traveling at 20 m/s, s = 20^2/(2*10) = 20 m and for the train traveling at 40 m/s, s = 40^2/(2*10) = 80. Adding the two gives 100 m. When the trains come to a stop they are 5 m apart.

The two trains do not collide.

Join to answer this question

Join a community of thousands of dedicated teachers and students.

Join eNotes