- #1
Adoniram
- 94
- 6
Homework Statement
A rod of length L is fixed at one end, and rotates in the X-Y plane with angular velocity ω. (To be clear, it is sweeping out an area of ##π (L/2)^{2}##.) A bead starts at position ##r(0)=L/2## with ##\dot{r}(0)=0##. Find ##r(t)## and the time it takes for the bead to fly off the end of the rod.
Homework Equations
##F=ma##
The Attempt at a Solution
First, I wanted to find an expression for the velocity of the bead in general:
##v(t)=\dot{r}\hat{r}+rω\hat{φ}##
Then I find the acceleration of such a situation:
##a(t)=(\ddot{r}-ω^{2}r)\hat{r}+(2ω\dot{r})\hat{φ}##
Then I need to apply the 2nd law and solve the diff eq. My question at this point is: Is this problem readily solvable in this coordinate system, or do I need to switch to something else like ##r(φ)## first?
I've played with a few attempts, and my best guess right now is:
##\dot{r}(t)=(L/2)e^{(ω/m)t}##
or
##\dot{r}(t)=(L/2)e^{(2ω/m)t}##
(and of course the position is just the integral of that)
But I'm not really confident on that answer...