Rotational Motion Homework: Angular Momentum and Tension

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SUMMARY

The discussion centers on a lab experiment involving a wheel and a weight tied to a string, exploring the conservation of angular momentum and the constancy of tension in the string. The participant questions whether the angular momentum of the system, comprising the wheel and the mass, is conserved, concluding it is not due to gravitational acceleration. Additionally, they assert that the tension in the string remains constant, equating it to the weight's mass multiplied by 9.8 m/s². The conversation emphasizes the importance of drawing free body diagrams (FBDs) and applying equations of motion for accurate analysis.

PREREQUISITES
  • Understanding of angular momentum and its conservation principles
  • Familiarity with torque calculations and the equation |Torque|=|F||r|sin(θ)
  • Knowledge of free body diagrams (FBDs) and their application in mechanics
  • Basic grasp of Newton's laws of motion and gravitational force
NEXT STEPS
  • Study the principles of angular momentum conservation in rotational systems
  • Learn how to construct and analyze free body diagrams (FBDs) for complex systems
  • Explore the relationship between torque and angular acceleration in rotational dynamics
  • Investigate the effects of tension in strings under various conditions in physics problems
USEFUL FOR

Students studying physics, particularly those focusing on rotational motion, mechanics, and lab experiments involving angular momentum and tension analysis.

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Homework Statement



I did a lab today where a weight was tied to a string. The string was wrapped around part of the circumference of a wheel, and then the end was taped down. So, when I let go of the wheel and the weight, the force of gravity on the weight causes the wheel to turn. I have two questions:

1. Is the angular momentum of the system made up of the wheel and the mass conserved?
2, Is the tension in the string constant?

Homework Equations



|Torque|=|F||r|sin(θ)
Angular momentum=I*[tex]\omega[/tex]

The Attempt at a Solution



1. I think it isn't conserved because the force of gravity acting on the mass accelerates the system, making angular momentum not be conserved.
2. The tension is constant because it equals the mass of the weight times 9.8.
 
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You say "the end was taped down." Do you mean the end of the string was taped down? If so, how did this permit the system to move?

With regard to the tension in the string, draw some FBDs and write some equations of motion before you jump to a conclusion here.
 

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