HSC Science (Electronics) 12th Board ExamMaharashtra State Board
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# Obtain an Expression for Total Kinetic Energy of a Rolling Body - HSC Science (Electronics) 12th Board Exam - Physics

ConceptDefinition of M.I., K.E. of Rotating Body

#### Question

Obtain an expression for total kinetic energy of a rolling body in the form

1/2 (MV^2)[1+K^2/R^2]

#### Solution

Let M and R be the mass and radius of the body, V is the translation speed, ω is the angular speed and I is the moment of inertia of the body about an axis passing through the centre of mass.

Kinetic energy of rotation, E_R=1/2MV^2

Kinetic energy of translation, E_r=1/2Iomega^2

Thus, the total kinetic energy 'E' of the rolling body is

E = ER + Er

=1/2MV^2+1/2Iomega^2

=1/2MV^2+1/2MK^2omega^2 ......(I=MK^2 " and K is the radius of gyration")

=1/2MR^2omega^2+1/2MK^2omega^2 ........(V=Romega)

:.E=1/2Momega^2(R^2+K^2)

:.E=1/2MV^2/R^2(R^2+K^2)

E=1/2MV^2(1+K^2/R^2)

Hence proved.

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#### APPEARS IN

2015-2016 (March) (with solutions)
Question 1.3 | 2.00 marks

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Solution Obtain an Expression for Total Kinetic Energy of a Rolling Body Concept: Definition of M.I., K.E. of Rotating Body.
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