What should be the free body diagram?

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Homework Help Overview

The discussion revolves around analyzing a system involving two blocks (M1 and M2) connected by pulleys, with given masses and friction coefficients. The goal is to identify the forces acting on each block and understand the dynamics of the system under the influence of an external force.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the forces acting on both blocks, including the effects of friction and tension in the ropes. There is a focus on the direction and magnitude of these forces, particularly concerning the pulleys and their role in the system.

Discussion Status

Some participants have offered insights into the forces acting on the pulleys and their interaction with the blocks. There is an ongoing exploration of the implications of assuming frictionless pulleys and how that affects the forces on the blocks. Multiple interpretations of the forces at play are being examined.

Contextual Notes

Participants are working with specific values for mass and friction, and there is an assumption that the pulleys are frictionless and of negligible mass. The discussion includes considerations of the forces exerted by the pulleys on the blocks.

AlchemistK
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Homework Statement


The Question gives some data, and a figure to find out the acceleration.
In the arrangement shown (refer attachment) shown, M1=20kg, M2=30Kg, floor is smooth and friction between two blocks: μ(s) = 0.6, μ(k) = 0.4.
F= 400N
What are the forces acting on the two blocks?

Homework Equations


The Attempt at a Solution


On M1, there is F acting towards right, and the friction towards the left.
For M2, There is the friction acting towards right, and then the forces exerted by the pulleys.
In what direction and magnitude do they act?
 

Attachments

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I'm assuming the pulleys are frictionless and have negligible mass.

Then the tension in the rope in all locations is F .

Forces exerted on the upper pulley: The rope exerts a force (equal to F) downward and a force, F to the left.

Forces exerted on the lower pulley: What do you think?

The pulleys may be considered as part of Block 1 .

https://www.physicsforums.com/attachment.php?attachmentid=40217&d=1319254345
 
The force by the pulley on the lower block will be F towards the right, and F downwards.
Meaning that in the direction parallel to the floor, only the reaction of the friction force between M1 and M2 will act on M2,to the right, right?
 
AlchemistK said:
The force by the pulley on the lower block will be F towards the right, and F [STRIKE]downwards[/STRIKE]. upward
Meaning that in the direction parallel to the floor, only the reaction of the friction force between M1 and M2 will act on M2,to the right, right?

So the net force that the rope exerts on block #2, via the pulleys, is zero.
 

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