Kinetic energy and rigid bodies

AI Thread Summary
Kinetic energy in rigid bodies must specify both the axis of rotation and the point about which the body rotates, as the moment of inertia varies with these parameters. The formula K = ½ * I * w^2 requires clarity on the axis to accurately calculate kinetic energy. Without this specification, the kinetic energy value may be misleading or incorrect. Understanding these details is crucial for proper analysis in physics. Therefore, it is essential to define the axis and point of rotation when discussing kinetic energy.
Niles
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Homework Statement


Does it make sense to talk about kinetic energy without specifying, which axis the body is rotation about? I mean, since K = ½ * I * w^2, I have to say that " ... the kinetic energy of the body around the x-axis is ...", right?
 
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Niles said:

Homework Statement


Does it make sense to talk about kinetic energy without specifying, which axis the body is rotation about? I mean, since K = ½ * I * w^2, I have to say that " ... the kinetic energy of the body around the x-axis is ...", right?

Not only you have to say around what axis it is rotating but in addition you have to say around what point! In other words, you have to specify completely the axis around which the object rotates (and notice that the value of the moment of inertia depends on what is the axis around which the object revolves).
 
Ok, good - then I have understood it correctly :-)

Thanks!
 

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