Solve Dynamics Problem: Find Friction Force at θ=80° & 40°

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AI Thread Summary
The discussion focuses on solving a dynamics problem involving a mass (E) moving along a semicircular path on a rotating plate. The user seeks to determine if E will move at angles θ = 80° and θ = 40°, as well as calculate the friction force's magnitude and direction. They have applied Newton's second law and provided equations for the forces acting on E, including weight, normal forces, and friction. The user is looking for assistance in completing the calculations and understanding the dynamics involved. The thread highlights the need for clarification on the application of rotational dynamics principles in this context.
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Homework Statement


I drew this to make it easier to understand:
http://img142.imageshack.us/img142/2729/problemagc0.th.jpg
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.

Homework Equations


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

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) iI hope you can help me out here. Thanks a lot!
 
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Bump, anyone?
Thanks again.
 
Bump, please give me a hand...
 

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