Calculating Tension with Kinetic Friction in a Pulley

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SUMMARY

The discussion focuses on calculating tension in a pulley system involving kinetic and static friction. For the first scenario, the tension was calculated using the formula T=mg, resulting in 0.618N, while static friction was determined to be 0.745N. In the second scenario, the tension was initially calculated as 0.471N, but after reevaluation using T=mg+Fs, the tension was found to be 1.22N, yielding a kinetic friction value of 0.143N, which aligns with the principle that kinetic friction is less than static friction. The correct approach for calculating tension in kinetic scenarios involves accounting for both gravitational force and static friction.

PREREQUISITES
  • Understanding of Newton's laws of motion
  • Familiarity with concepts of static and kinetic friction
  • Knowledge of tension in pulley systems
  • Ability to apply trigonometric functions in physics problems
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  • Study the principles of Newton's second law in pulley systems
  • Learn about the differences between static and kinetic friction coefficients
  • Explore the application of trigonometric functions in inclined plane problems
  • Review lab experiments related to inclined planes and friction
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Homework Statement


(1) Firstly, the block as it rest at incline of 10 degrees and mass is added on the other side of pulley to overcome static friction (0.0063kg). The block weighs 0.8kg. Calculate the tension.

(2) The block is at same angle and mass but this time the block was lightly pushed from back to make it move. As the block began to move, mass was added on the other side of the pulley to just keep moving it forward. The mass was (0.00480kg). Calculate Tension.

Homework Equations


T=mg (to calculate tension for static friction)
T=mg+Fs
Fs=T-Fgsin@
Fk=T-Fgsin@

The Attempt at a Solution


For (1), I used T=mg to find tension which comes out to be 0.618N. I used that value to find Static Friction and I got 0.745N

For (2), I tried using T=mg to find Tension and I got 0.471N but when I used that value to find Kinetic friction, I'm getting 0.892N. This value didn't make sense because the Kinetic friction is always less than static friction but here it was higher.

So, I tried using T=mg+Fs for tension in Kinetic friction. I assumed that Fs was force applied because the cart was slightly pushed just o make it move. By using that, I got T=1.22N. I used that value to find Kinetic friction and I'm getting 0.143N. This value makes sense to me because the kinetic friction is lower than static.

The questions are very similar to this lab: http://ems.calumet.purdue.edu/chemphys/ncrelich/PortableDocuments/PHYS152/Summer2009/LabInclinedPlane.pdf

So, can you please let me know which method is right in order to calculate Tension for Kinetic part. Thanks a lot.
 
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(1) Firstly, the block as it rest at incline of 10 degrees and mass is added on the other side of pulley to overcome static friction (0.0063kg). The block weighs 0.8kg. Calculate the tension.

Then the tension is g*0.0063kg+g*0.8kg*sin10°
Do you agree ?
 
Since the mass on the pulley is the one that made the block start moving. I think that the tension produced by that mass includes Force of gravity in the X and static friction of the block. That's why the equation I used is T=mg.
 

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