physics question regarding velocity?

J

Jill Z

New member
Two locomotives approach each other on parallel tracks. Each has a speed of v = 80 km/h with respect to the ground. If they are initially d = 7.0 km apart, how long will it be before they reach each other?
express your answer in minutes.
i'm so confused and would appreciate if someone took me step by step through this problem. thanks!
 
The locomotives approach each other.
Therefore relative speed = v + v = 2v = 2 * 80 = 160 km/h
Distance = 7.0 km
Time = distance/relative speed = 7.0/160 hr = 0.04375 hr
= 0.04375 * 60 minute = 2.625 min

Ans: 2.625 min
(can round off to 2.6 min)
 
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