Dynamics question regarding moment of inertia

AI Thread Summary
The discussion revolves around a dynamics problem involving the calculation of angular acceleration, frictional force, and the acceleration of point G. The user successfully calculated the friction force and acceleration but found the angular acceleration to be incorrect. They provided their equations for force and moment analysis, indicating that their calculations led to an angular acceleration of 8.84, while the expected value was 0.295. A question was raised regarding the use of cos(30) in the equations, suggesting a need for clarification on its application in the context of the problem. The conversation highlights the complexities of dynamics problems and the importance of accurate calculations in determining angular motion.
chicagobears34
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Hi, I have a question regarding a dynamics question that be found here:http://by.genie.uottawa.ca/~mess/files/MCG_2107/MCG2107_M2005_p2.pdf, It is the first problem on that link (labeled number 2.)

I did ƩFx, ƩFy, ƩMG which allowed me to find angular acceleration, frictional force, and acceleration of G.
Friction force and acceleration of G were correct but angular acceleration was wrong.
My equations were:
ƩFx: -μkN + T cos(30)=maG
ƩFy: N-mg+Tsin(30)=0
ƩMG: Tcos(30)(0.075)-μkN(0.2)=Iα
ΔFf=17.6N, Ag=1.0281, α=8.84
α should be equal to .295
 
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hi chicagobears34! :smile:
chicagobears34 said:
ƩMG: Tcos(30)(0.075)-μkN(0.2)=Iα

why cos(30) ? :wink:
 
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