Question

A train leaves Little Rock, Arkansas, and travels north at 60 kilometers per hour. Another train leaves at the same time & travels south at 65 kilometers per hour. How long will it take before they are 500 kilometers apart?

Answer 1

3.704 Hours

Explanation:

This problem can be solved by using concept of relative speed. relative speed is speed of one body in comparison of other.

If two bodies are moving in same direction their relative speed is calculated by taking difference of each other speed.

If two bodies are moving in opposite direction their relative speed is calculated by taking sum of each other speed.

In the problem stated two bodies are moving in north and south direction, hence they are moving in opposite direction, thus their speed can be taken sum of individual speed.

which is

(60+65) Km/Hr = 135 km/hour

Now given in question distance between two bodies is 500 KM

and relative speed = 135 km/hour

using formula of speed distance and time

Time = distance / speed = 500/135 = 3.704 Hours

Therefore it will take 3.704 Hours for both of the trains to be 500 km apart.