Posted by **jake** on Sunday, February 7, 2010 at 8:46pm.

Need help with this short physics question

there is a race betwen person A and person B. They both start at the same time, but B initial position is 10m left of peron A. person A travels 100 meters right in 20 seonds, Person Btravels 112.5 meters right in 15 seconds.

what is the time, postion and, and person B displacement at which Person B catches up with Person A

- physics -
**Anonymous**, Sunday, February 7, 2010 at 9:16pm
Consider person A's starting position to be 0.

for person A, d = r * t

d = 100 meters / 20 sec * t

d = 5 meters / sec * t

for person B, d = 10 + (d * t)

d = 10 + (112.5 meters / 15 sec * t)

d = 10 + (7.5 meters / sec * t)

We know the two positions are equal when person A catches person B. So.

5 meters / sec * t = 10 + (7.5 meters / sec * t)

solving that will give you t.

To find the distance, use the simpler of the 2 original equations:

d = 5 meters / sec * t

- physics -
**jake**, Sunday, February 7, 2010 at 10:26pm
i don't get how to find the time

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