# Thread: relative rate of moving problem

1. ## relative rate of moving problem

A man starts walking north at 1.2 m/s from a point P. Five minutes later a woman starts walking south at 1.6 m/s from a point 200 m due east of P. At what rate are the peoplemoving apart 15 min after the woman starts walking?

2. ## Re: relative rate of moving problem

Where the unit vector in the North direction is j the man's velocity is 1.2j, the woman's velocity is -1.6j. The velocity of the man relative to the woman is 1.2j-(-1.6j)= 2.8j
Find out if they have passed each other after 15 minutes, if they have passed each other then they are moving away from each other at 2.8j, if they have not passed each other they are moving towards each other at 2.8j

3. ## Re: relative rate of moving problem

Shakarri, you seem to have missed that the woman is walking on a line that is 200m east of the line on which the man is walking.

asifrhaman1988, you should probably draw a diagram first, then express the distance between the man and the woman in terms of t, the number of minutes after the woman starts walking (you will need to use the Pythagorean Theorem). Then take the derivative and set t to 9000 (15 minutes times 60 seconds/minute).

- Hollywood