Angular speed people walking problem

[sweedeljoseph]

Homework Statement

Two people start at the same place and walk around a circular lake in opposite directions. One has an angular speed of 1.7*10^-3 rad/s, while the other has an angular speed of 3.4*10^-3 rad/s. How long will it be before they meet?

Homework Equations

w=\theta/Delta t
*v=v_o+at ~ w=w_o+\omegat
*v²=v_o²+2ax ~ w²=w_o²+2\omega\theta
*x=v_ot+(1/2)at² ~ \theta=w_ot+(1/2)at²

the ones with * means i changed it to what the problem is about. means the same thing just different letters so you won't get confused i guess.

The Attempt at a Solution

how do you set that up in the problem i gave because there's no value that is for rad/s. or is that omega? you plug that in there? because the seconds are supposed to be squared. I am so lost. i just learned this today too. its great. please help!

thank you!
sweedeljoseph

 

[montoyas7940]

This is similar to your bullet problem. You have a speed and a distance but you need a time. Do you know the total distance? Do you know the total speed?

 

[LowlyPion]

How many radians are they apart when they start? 1 revolution is how many radians?

How fast are the walking toward each other? How many radians per second are the closing on each other?

Distance/speed = time doesn't it?

 

[sweedeljoseph]

i don't know the distance or speed. all the information i had i gave. it was word for word from the problem. there's no extra reference or anything.

 

[montoyas7940]

Your angular distance is all the way around the circle, or 2 pi radians. The total speed is the speed of the two walkers added together. They are starting back to back walking away from each other around a circular lake.

Maybe it will help you to draw a diagram of the problem...

 

[LowlyPion]

i don't know the distance or speed. all the information i had i gave. it was word for word from the problem. there's no extra reference or anything.

Gee it looks like you are given their angular rates of walking about the lake.

And you know how many radians there are in one revolution.

You have all you need.

 

[sweedeljoseph]

i know the rates and there like 6.28 radians in one revolution. but what equation am i supposed to use?

 

[montoyas7940]

Do you know what each one means? Which one makes sense given the problem you are trying to solve and the information provided?

 

[LowlyPion]

i know the rates and there like 6.28 radians in one revolution. but what equation am i supposed to use?

ω * t = θ = 2π

You know what their rate of walking toward each other is.

 

[sweedeljoseph]

no i don't know what they mean. i just started learning this today and i have no idea what I am doing.