Angular Velocity and Angular Acceleration help

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In the discussion about angular velocity and acceleration, participants analyze four scenarios involving a fan's rotation. They establish that angular acceleration is positive when the fan speeds up in the counterclockwise direction and slows down in the clockwise direction. The consensus leans towards options II and III as the correct answers, indicating a clear understanding of the relationship between direction and angular acceleration. The conversation emphasizes the distinction between positive and negative angular acceleration based on rotation direction. Overall, the key takeaway is the identification of specific conditions under which angular acceleration is considered positive.
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Homework Statement



Consider four situations: I) a fan's rotation is speeding up while going in the clockwise direction; II) it is speeding up while going in the counterclockwise direction; III) it is slowing down while going in the clockwise direction; and IV) it is slowing down while going in the counterclockwise direction. In which cases is the angular acceleration positive?

I & II

III & IV

II & III

I & IV

Angular acceleration is always positive


Homework Equations



I know that angular counter clock wise acceleration is positive and clockwise is negative...

The Attempt at a Solution

 
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so what do you think the correct answer is
 
2 and 3
 
layla2525 said:
2 and 3

so like is that a guess or do you have reasons for picking those?
 

Thread 'Magnitude of buoyant force in fluids of different densities'

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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