Solving Angular Velocity Homework: Mass, Friction & Work

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SUMMARY

The discussion focuses on solving a physics homework problem involving a puck of mass 0.5 kg executing uniform circular motion with an angular frequency of 10 sec-1 and a radius of 0.8 m. The student is tasked with calculating the work done when the string is pulled down by 0.5 m. Key equations utilized include the kinetic energy formula and the moment of inertia, specifically I = mr2. The challenge lies in determining the final angular velocity after the string is pulled.

PREREQUISITES
  • Understanding of kinetic energy (KE) equations
  • Familiarity with angular momentum conservation principles
  • Knowledge of moment of inertia calculations
  • Basic grasp of uniform circular motion concepts
NEXT STEPS
  • Study the conservation of angular momentum in detail
  • Learn how to calculate moment of inertia for different shapes
  • Explore the relationship between angular velocity and linear velocity
  • Review work-energy principles in rotational motion
USEFUL FOR

Students studying physics, particularly those focusing on mechanics and rotational dynamics, as well as educators looking for examples of angular motion problems.

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Homework Statement


a small puck of mass .5kg is executing Uniform constant motion on a friction free horizontal table. The angular frequency of the puck is 10 sec-1 (counter clockwise) and the radius of the circular motion is .8m. the radius stays fixed as the student holds the string in place. he now pulls the string down .5 m and holds it again in place. what work did he do?


Homework Equations



KE(original)+ W = KE (final)
inertia of hockey puck on string = mr2
w = angular velocity
I = inertia

The Attempt at a Solution


KE(original)+ W = KE (final)
.5(I)w2 +W = KE final
.5 (.5)(.8)2(102) + W = KE final

now i have a problem solving for kinetic energy final...
KE final = .5(.5)(.5)2(102)(w2)
I can't figure out what w (angular velocity) is...
please help!
 
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Have you tried using the conservation of angular momentum?
 

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