What is the angular momentum of the record?

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SUMMARY

The angular momentum of a .019 kg record with a 15 cm radius rotating at 33 1/3 rpm is calculated using the formula L = Iw, where I is the moment of inertia and w is the angular speed in radians per second. The correct moment of inertia for a solid disk is I = 0.5mr². After correcting the angular speed conversion from 33.33 rpm to radians per second, the accurate angular momentum is determined to be 7.5 x 10^-4 kg·m²/s.

PREREQUISITES
  • Understanding of angular momentum (L = Iw)
  • Knowledge of moment of inertia for solid disks (I = 0.5mr²)
  • Ability to convert revolutions per minute (rpm) to radians per second
  • Basic physics concepts related to rotational motion
NEXT STEPS
  • Learn how to convert rpm to radians per second accurately
  • Study the derivation of the moment of inertia for different shapes
  • Explore applications of angular momentum in real-world scenarios
  • Investigate the effects of varying mass and radius on angular momentum
USEFUL FOR

Students studying physics, particularly those focusing on rotational dynamics, as well as educators looking for clear examples of angular momentum calculations.

ryty
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Homework Statement


A .019 kg record with a 15 cm radius rotates with an angular speed of 33 1/3 rpm. What is the angular momentum?


Homework Equations


L=Iw I=mr^2 w=(33.33/60)*2pi=3.17 rad/s


The Attempt at a Solution


L=(.019*.15^2)(3.17)
L=.0004275*3.17
L=.00136
but that's wrong, and i don't know why
 
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ryty said:

Homework Statement


A .019 kg record with a 15 cm radius rotates with an angular speed of 33 1/3 rpm. What is the angular momentum?


Homework Equations


L=Iw I=mr^2 w=(33.33/60)*2pi=3.17 rad/s


The Attempt at a Solution


L=(.019*.15^2)(3.17)
L=.0004275*3.17
L=.00136
but that's wrong, and i don't know why

Check your calculation of your conversion to rad/s, I get a different number. Also, check that you are using the appropriate formula for the moment of inertia. Are you assuming the record is a solid disk? If so, your formula for I is not quite right.
 
thanks i figured it out, i accidently udes 30.33, not 33.33, and i found the right equation
I=.5mr^2, and the right answer is 7.5x10^-4, thanks for your help
 

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