Rotation: Calculating Rotational Energy of Sphere with Steiner

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SUMMARY

The discussion focuses on calculating the rotational energy of a sphere with a moment of inertia of \( \frac{2}{5}mr^2 \) as it rolls down a frictionless plane. The relevant equation for rotational energy is \( E_{rot} = \frac{1}{2}I\omega^2 \). The main point of confusion is whether to apply Steiner's theorem in this scenario. It is established that Steiner's theorem is not necessary when calculating the rotational energy for a sphere rolling without friction, as the moment of inertia is already defined for the center of mass.

PREREQUISITES
  • Understanding of rotational dynamics
  • Familiarity with the moment of inertia
  • Knowledge of angular velocity and its relation to linear velocity
  • Basic principles of Steiner's theorem
NEXT STEPS
  • Study the application of Steiner's theorem in various rotational motion scenarios
  • Explore the relationship between linear and angular motion in rolling objects
  • Learn about the derivation of the moment of inertia for different shapes
  • Investigate energy conservation principles in rolling motion
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This discussion is beneficial for physics students, educators, and anyone interested in understanding the principles of rotational dynamics and energy calculations in rolling objects.

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Homework Statement



Consider a spere with momenta of inertia of 2/5*m*r^2 that rolls down a plane surface (no friction). I want to calculate the rotational energy of the sphere when it has speed v0.

Homework Equations



Erot=1/2*I*w^2

The Attempt at a Solution



My only problem is: Do I need to transform my I=2/5*m*r^2 with the rule of steiner, or don't I have to use the rule of Steiner? I would say no.
 
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I'm so confused because sometimes Steiner's theorem isn't used and sometimes it is used for rolling objects. Can you please generalize, when I have to use Steiner's theorem for rolling objects? Would be really helpful.
 

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