EK 1001 Physics #471 (The Pulley of Doom)

[MedGrl@2022]

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Hey everyone I am having some difficulty figuring out this tension/pulley problem in Physics EK 1001 #471 on page 49.

The question asks for the tension T in the rope?

Please refer to the picture and the answer in the EK book I could not completely understand their answer.

How I am I supposed to know how to set up the equations for this problem? How am I supposed to know which side to add ma? I am unsure which one has less force. Is there a way that I should intuitively figure out which side will have less force and accelerate downward? Is the pulley in equilibrium or is the left mass or right mass accelerating downward? Why does the right side accelerate twice as fast as the left side? Are all the tensions in a pulley (for all pulleys) the same?

Thank you for all your help.

Sincerely,

Verónica👍

 

[MedGrl@2022]

Hey everyone I am having some difficulty figuring out this tension/pulley problem in Physics EK 1001 #471 on page 49.

The question asks for the tension T in the rope?

Please refer to the picture and the answer in the EK book I could not completely understand their answer.

How I am I supposed to know how to set up the equations for this problem? How am I supposed to know which side to add ma? I am unsure which one has less force. Is there a way that I should intuitively figure out which side will have less force and accelerate downward? Is the pulley in equilibrium or is the left mass or right mass accelerating downward? Why does the right side accelerate twice as fast as the left side? Are all the tensions in a pulley (for all pulleys) the same?

Thank you for all your help.

Sincerely,

Verónica👍

In addition, how am I supposed to know that the machine in #472 is analogous to the pulley in question #471?

I really hope someone can help me with this!

Thank you,

Verónica

 

[Gauss44]

How am I supposed to know which side to add ma? Ma is a downward force so it would be on the same side of the equation as mg.

I am unsure which one has less force. Is there a way that I should intuitively figure out which side will have less force and accelerate downward? Yes, since both weights are equal, next look at the number of cables connected to the weights. One weight has one cable or one source of upward tension. The other has two sources of upward tension (sort of the same rope wrapped around the pulley, it counts as 2 sources of tension). 1T<2T so the left side connected to one tension source will accelerate downward).

Is the pulley in equilibrium or is the left mass or right mass accelerating downward? Left is accelerating downward.

Why does the right side accelerate twice as fast as the left side? The left side accelerates twice as fast as the right side because for every inch of rope that's pulled over the top pully, the left weight falls 1 inch and the right weight rises one-half inch.

Are all the tensions in a pulley (for all pulleys) the same? The tension in all 3 sections of the rope is the same.