Magnitude of Frictional Force in Simple Harmonic Motion

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The discussion revolves around understanding the frictional force in simple harmonic motion (SHM) through a series of sub-questions. It highlights that the velocity and acceleration of a block in SHM vary as it oscillates, affecting the frictional force experienced. The participants clarify that when two blocks move together in SHM, the acceleration of one block can influence the likelihood of slipping. Specifically, block A is more prone to slip when block B reaches a certain position due to its greater acceleration at that point. Overall, the conversation emphasizes the relationship between varying acceleration and frictional forces in SHM scenarios.
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Homework Statement


upload_2017-6-11_1-11-47.png


I do not fully grasp the concept behind all of these sub questions (i)-(iv).

Homework Equations


v=wAcos(wt) (SMH)?
Friction Force = Coefficient of Friction * Normal Force

The Attempt at a Solution



(i) Varying as simple harmonic motion sees varying acceleration as it oscillates forwards, until a stationary point and then backwards.

(ii) Same (not varying) as block A moves with block B, in identical harmonic motion?

(iii) I think this has to do with the result of (ii), which would indicate (ii)'s correct answer is 'varying' but I am not sure why (conceptually).

(iv) as (iii)
 
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F=ma. If a is varying, what can be said about F?
 
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jbriggs444 said:
F=ma. If a is varying, what can be said about F?
I see, very simple. Thank you!

So for (iii), block A would be more likely to slip when block B is at x=d because at x=d block B would have greater acceleration (would it?)
 
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Rotnort said:
I see, very simple. Thank you!

So for (iii), block A would be more likely to slip when block B is at x=d because at x=d block B would have greater acceleration (would it?)
Yes!
 
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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