Rotational K.E. of a disc is:
Correct answer: B. K.E.rot =1/3 mv2
- A. K.E.rot =1/2 mv2
- B. K.E.rot =1/3 mv2
- C. K.E.rot =1/4 mv2
- D. None
Explanation
The correct formula for the rotational kinetic energy (K.E.rot ) of a rotating disc is:K.E.rot =1/2 Iω2The moment of inertia (I) for a disc rotating about its central axis is 1/2 mr2, where m is the mass of the disc and r is the radius.Substituting this into the rotational kinetic energy formula, we get:K.E.rot =1/4 mv2
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Rotational motion relates angular displacement, angular velocity and angular acceleration to linear displacement, tangential velocity and tangential acceleration through the radius. Questions use radians, v equals r omega and tangential acceleration, while distinguishing tangential velocity from centripetal acceleration and angular quantities from their linear counterparts.
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