Relative Motion Analysis: Acceleration of rotating disk

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The discussion revolves around determining the angular velocity and acceleration of a slotted link driven by a rotating disk. The user expresses confusion about how to approach the problem, considering both graphical methods and the possibility of using an acceleration diagram. Suggestions include analyzing the link's angle as a function of time and differentiating it to find the necessary values. There is also a consideration of treating the system as a crank and slotted lever mechanism for analysis. Overall, the thread emphasizes exploring different analytical approaches to solve the problem effectively.
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Homework Statement


A slotted link AC is is driven by the peg P connected to a rotating disk. Point A is fixed. Determine the link's angular velocity, \omega_{ac} and acceleration, \alpha_{ac} when the angular velocity and acceleration are \omega and \alpha, respectively.
\omega = 6 \frac{rad}{s} CCW
\alpha = 10 \frac{rad}{s^2} CCW
l_{ap} = 0.75 \hspace{1 mm} m
r_{op} = 0.30 \hspace{1 mm} m
\theta = \frac{\pi}{6}
kBBmaLU.png


Homework Equations

The Attempt at a Solution


First, I should state that I am genuinely lost on this problem. I am not sure at all how to go about finding the angular velocity for this one. For the acceleration I was thinking that I could perhaps draw an acceleration diagram and attempt to find the solution that way. Maybe I could do something similar for the velocity? I was hoping someone could sort of push me in the right direction/inform me whether there is a better way to solve this rather than a graphical approach. Any help at all is greatly appreciated. Thanks.
 
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The diagram uses theta for two different things... probably because they have the same size at t=0.
Play with the setup for different angles to P ... OP has a constand angular velocity so you can redo the sketch for equal times ans get a feel for what is happening.
There are several approaches but try finding the equation of the angle of the link as a function of time aband differentiating.
 
Simon Bridge said:
The diagram uses theta for two different things... probably because they have the same size at t=0.
Play with the setup for different angles to P ... OP has a constand angular velocity so you can redo the sketch for equal times ans get a feel for what is happening.
There are several approaches but try finding the equation of the angle of the link as a function of time aband differentiating.
Awesome, thanks for the reply. One thought I did have was to consider this as a crank and slotted lever mechanism, where the disk is the crank. Could I do an analysis this way? Or would it be too inaccurate?
 
Maybe - I'd do it directly by geometry myself.
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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