Engineering Rigid body Newton’s law homework

AI Thread Summary
The discussion revolves around understanding concepts related to rigid body motion and Newton's laws in a homework context. Key points include the identification of centripetal motion in a rod, the reasoning behind zero angular acceleration when using moments about point G, and the clarification of the rod's radius as 0.4 due to the motion of its ends. Participants express urgency in solving problems for an upcoming test and share insights on the fixed angle of the rod preventing rotation. Overall, the conversation highlights the complexities of rigid body dynamics and the need for peer support in mastering the material.
Pipsqueakalchemist
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Homework Statement
Problem and solution below
Relevant Equations
F = ma
Moment equation
For this problem I know how to get the answers but I have a few things I’m not 100% sure about. First how do we know that the rod is experiencing centripetal motion? Second, when using moment about point G how do we know that the angular acceleration is equal to zero? And third the radius is 0.4 because the two ends of the rod are in motion with radius of 0.4 right?
 

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1. Because 200 N + 300 N > mg
2. Because the ropes fix the angle of the rod ##\rightarrow## it can't rotate around G
3. Yes
Pipsqueakalchemist said:
I know how to get the answers
yea, because it seems you have a solutions manual at your disposition ? PF rules in fact require you to post your own attempt at solution :smile:
 
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Well my test is on Monday and I still have another 10 question in the problem set. I can’t afford to get stuck on every single question.
 
I see. Was my reply in #2 ok with you ?

##\ ##
 
Yea I guess I see it. Since the bar isn’t rotating around point G or around any point on the bar itself so regardless of which point I chose the angular acceleration will always be zero right?
 
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Hey you commented on my other post. The one with the tipping cabinet. Do you mind looking at it because I still have some confusion.
 
Pipsqueakalchemist said:
Hey you commented on my other post. The one with the tipping cabinet. Do you mind looking at it because I still have some confusion.
Me too. :frown:
 
Lol, yea Ik the signs don’t make sense
 
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