(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Hello everyone. I'm studying engineering and I'm doing calculus this year and next year as part of my degree. We get problem sheets with lots of exercises to do as practice. I'm using the James Stewart Calculus and Concepts textbook.

Anyway, I got stuck on the following question in my problem sheet.

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

2. Relevant equations

3. The attempt at a solution

So I drew point P on a piece of paper. The rate at which the two people are moving apart is their velocity right? their distance with respect to time. So if I let S(t) equal 1.2t + 1.6t + (dist he has traveled after 5 minutes) + (distance between them at the start) I would get S(t) = (1.2t + 1.6t + 360) + 200.

I must be missing something because then the derivative will be a constant...

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: A calculus problem

**Physics Forums | Science Articles, Homework Help, Discussion**