Can someone check if this forces problem on an incline

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The discussion focuses on verifying the calculations related to a force problem involving a block on an incline. Participants question the correctness of the force P and its dependence on the angle θ, suggesting the need for free body diagrams for clarity. There is confusion regarding the mass used in the calculations, specifically the discrepancy between 2m and 3m. The importance of clearly identifying the forces acting on both the plank and the block is emphasized. The original poster plans to redo the problem and share the revised version for further feedback.
Blockade
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To me the force P that pulls the bottom block up the incline seems a little low. Can someone confirm with my setup and work in brown is correct? Thank you.

Problem:
8eea061f2a.jpg


Work:
4c89ea0207.png
 
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Would you expect P to be independent of ##\theta## ?
Draw a free body diagram for each of the blocks separately.
And I see one of the two blue arrows (the most illegible one :smile:) can't be right.
 
BvU said:
Would you expect P to be independent of ##\theta## ?
Draw a free body diagram for each of the blocks separately.
And I see one of the two blue arrows (the most illegible one :smile:) can't be right.

ΣFxA : P - T - (3mgsinθ) - μk mgcosθ= 0

That was your hint right XD.
 
Blockade said:
ΣFxA : P - T - (3mgsinθ) - μk mgcosθ= 0

That was your hint right XD.
How about clearly stating what forces act on the plank and what forces act on the block - separately.

The mass of the block is 2m, right. Why do you have 3m ?

The plank acts on the block via friction and via the tension in the cord.
 
4
SammyS said:
How about clearly stating what forces act on the plank and what forces act on the block - separately.

The mass of the block is 2m, right. Why do you have 3m ?

The plank acts on the block via friction and via the tension in the cord.

I will redo the problem and post it back up. Thanks for you input.
 

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