Rotational Inertia of Solid Disk

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SUMMARY

The rotational inertia of a solid iron disk with a mass of 46 kg, thickness of 6.31 cm, and radius of 19.4 cm can be calculated using the formula I = 1/2MR². This formula applies directly to solid disks and simplifies the calculation of rotational inertia about an axis through its center. The discussion emphasizes the importance of integrating concentric slices to derive the inertia for varying thicknesses, which is a common approach in physics problems involving rotational dynamics.

PREREQUISITES
  • Understanding of rotational inertia and its significance in physics.
  • Familiarity with the formula I = 1/2MR² for solid disks.
  • Basic knowledge of calculus, specifically integration techniques.
  • Concept of concentric slices in geometric analysis.
NEXT STEPS
  • Study the derivation of the rotational inertia formula for different shapes, including disks and cylinders.
  • Learn about the application of integration in physics problems, particularly in rotational dynamics.
  • Explore examples of calculating rotational inertia for composite shapes.
  • Investigate the physical significance of rotational inertia in real-world applications, such as machinery and vehicles.
USEFUL FOR

Students studying physics, particularly those focusing on mechanics, as well as educators looking for examples of rotational inertia calculations.

Kickbladesama
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Homework Statement



What is the rotational inertia of a solid iron disk of mass 46 kg, with a thickness of 6.31 cm and radius of 19.4 cm, about an axis through its center and perpendicular to it?

Homework Equations



either 1/2MR^(2) or I = sigma (1->N) Mi x Ri^(2)

The Attempt at a Solution


I don't know what to do!
 
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Welcome to PF!

Kickbladesama said:
What is the rotational inertia of a solid iron disk of mass 46 kg, with a thickness of 6.31 cm and radius of 19.4 cm, about an axis through its center and perpendicular to it?

Hi Kickbladesama! Welcome to PF! :smile:

Hint: divide the disc into concentric slices of thickness dr, and integrate. :wink:
 

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