What is the Correct Concept for Solving the Stacked Blocks Problem?

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SUMMARY

The discussion centers on the Stacked Blocks Problem in classical mechanics, specifically addressing the forces acting on two blocks, X and Y. The consensus is that when block X does not slip on block Y, friction exists, and the applied force F on block Y must be analyzed in conjunction with the frictional force acting on block X. The correct interpretation involves recognizing that the net horizontal force on block Y is F minus the friction force, which is crucial for understanding the system's acceleration. A free body diagram is recommended for clearer visualization of the forces involved.

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Homework Statement


177cf5c7d0.png


Homework Equations


F= ma[/B]

The Attempt at a Solution


X does not slip. so friction exists. Friction should be equal to the force F applied so that according to Newton's 3rd law, the friction and F cancel out and X remains on Y.
Is this the right concept?
 
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Arun Raja said:

Homework Statement


177cf5c7d0.png


Homework Equations


F= ma[/B]

The Attempt at a Solution


X does not slip. so friction exists. Friction should be equal to the force F applied so that according to Newton's 3rd law, the friction and F cancel out and X remains on Y.
Is this the right concept?
No. F is applied on Y. The friction between X and Y acts also on X. So the net horizontal force exerted on Y is F-friction. If F and the friction cancel out Y does not accelerate. As X moves together with Y the whole system stays in rest or moves without acceleration. But the problem stated that it accelerates.
X does not slip on Y means that they move together, with the same acceleration.
ehild
 
That would be fine if the boxes moved at a constant speed ... but they don't.
Instead, draw a free body diagram for each block.
 

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