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Home Q & A Board Science-Related Homework Help Physics
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Anonymous joshephn
wrote...
2 weeks ago
You're an investigator for the National Transportation Safety Board, examining a subway accident in which a train going at 82 km/h collided with a slower train traveling in the same direction at 26 km/h. Your job is to determine the relative speed of the collision to help establish new crash standards. The faster train's "black box" shows that its brakes were applied and it began slowing at the rate of 2.1 m/s^2 when it was 42 m from the slower train, while the slower train continued at constant speed.
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wrote...
#1
Educator
2 weeks ago Edited: 2 weeks ago, bio_man
Please see if this helps, I have attached the answer below:

This inspired my answer:
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Anonymous Author
wrote...
#2
2 weeks ago
Would the answer be the two velocities subtracted by each other as it is asking for relative speed of the collision? thanks for the help
wrote...
#3
Educator
2 weeks ago Edited: 2 weeks ago, bio_man
No, you pick the most reasonable time value. These values are telling you the time when the two trains will collide. It makes sense to pick the larger one because if you pick the shorter time, that means the faster train almost immediately hits the slower one that was initially 42 meters ahead.
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