# Dynamics problem

## Homework Statement

I drew this to make it easier to understand:
http://img142.imageshack.us/img142/2729/problemagc0.th.jpg [Broken]
E (mass: 400g) can move along the semicircle.
ABCD is a plate rotating around (AD) axis at constant speed (14 rad/s).
Coefficients of friction are 0.35 (static) and 0.25 (dynamic).
I need to find out whether E will move for θ = 80º and for θ = 40º. Also I need to find the module and direction of the friction force for t0.

None.

## The Attempt at a Solution

I applied Newton's second law.
Σ Fext = mg + N1 + N2 + f
Where:
mg is E's weight
N1 is the normal force in the (ABC) plane
N2 is the normal force perpendicular to the (ABC) plane
f is the friction force
I did this also so that you understand what I mean -just in case... :)
http://img88.imageshack.us/img88/4488/esquemabr8.th.jpg [Broken]

Then I think I must use:
aE = aO + aE/O + ωx(ωxOE) + αxOE + 2ωxvE/O
With:
α = dω/dt = 0
ω = 14 j
OE = (0.65 - sin(θ)*0.25) i

I hope you can help me out here. Thanks a lot!

Last edited by a moderator: