# Homework Help: Relative velocity and distance between particles

1. Aug 31, 2010

### vickyiit

1. The problem statement, all variables and given/known data

Lengths L₁, L₂. Velocities V₁, V₂.

2. Relevant equations

Find the shortest distance between particle A and B.

3. The attempt at a solution

[I seriously don't have any clue how to start this question itself.

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2. Aug 31, 2010

### N-Gin

You sholud first find the distance between the two given objects as a function of time. I'm not sure if $\theta$ in your picture is $90^{\circ}$ angle or not, but cosine rule will definitely work.

Then you find the first derivative of that function in order to find the time at which the distance is minimum. When you got that time, it's easy to find the distance by plugging it back to the distance function.