- #1

Stochastic13

- 60

- 0

## Homework Statement

Two cars start moving form the same place. One goes north at a rate of 50 mi/hr, while the other heads east at a rate of 30 mi/hr. At what rate is the distance between the two cars changing exactly two hours later?

## Homework Equations

## The Attempt at a Solution

I thought that the equation for the velocity vectors is:

r(x) = 30xi + 50yj

and thus distance d two hours later is given by:

d = √(30x² + 50x² )

and

dd/dt = ∂x/dt + ∂y/dt

and after solving the equation I just plug in 2 for x and y to get what time the distance changes at the two hour mark.

Is this right?