# Homework Help: Related Rate Question

1. May 1, 2012

### wild

Related Rate Question plz help!!

I am stuck on this question and need help asap plzz.

Mr. John is climbing a tree at a rate of 2m/s. After 1 second of climbing Mr. John is noticed by a 2m tall zombie that is 30m away from the tree. The zombie walks towards Mr. John at a rate of 5m/s. What is the rate of change of the distance between Mr. John and the zombie when the angle of elevation from the zombie to Mr. John is Pi/4.

i kno that
Dy/Dt = 2m/s.
Dx/Dt is 5m/s.
theta is Pi/4.
i just cant find out how to do this plzz help!!

2. May 2, 2012

### hamsterman

Re: Related Rate Question plz help!!

Write down functions j(t) and z(t), then find the derivative of $\sqrt{j^2(t) + z^2(t)}$. Note that j and z are lines in R^2 space. jx is always 0 and zy is probably 2.

3. May 2, 2012

Re: Related Rate Question plz help!!

Could you please draw out the situation and then post it up? It would be of big assistance.

4. May 2, 2012

### Staff: Mentor

Re: Related Rate Question plz help!!

Some of what you know isn't true! The angle is a function of time, and is $\pi/4$ only at one particular time. Also, since the zombie (who writes these problems?) is approaching the tree, dx/dt = -5 m/s.