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Two persons are to a run a race but one can run 10 meters per second, whereas the other can run 6 meters per second.
If the slower runner has a 70-meter head start, how long will it be before the
faster runner catches up to the slower runner, if they begin at the same time.
Let t = time (in sec) for the faster runner to catch the slower
When this occurs they will have ran the same distance, Write distance equation,
Dist = speed*time
10t = 6t + 70
10t - 6t = 70
4t = 70
t = 17.5 seconds
Check this using relative speed
their relative speed (to each other) is 4 m/sec
How long will it take to cover 70 m at 4 m/sec