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The oxygen molecule has a mass of 5.30 × 10–26 kg and a moment of inertia of 1.94×10–46 kg m2 about an axis through its centre perpendicular to the lines joining the two atoms. Suppose the mean speed of such a molecule in a gas is 500 m/s and that its kinetic energy of rotation is two thirds of its kinetic energy of translation. Find the average angular velocity of the molecule. |
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Answer» tion:Mass of an OXYGEN MOLECULE, m = 5.30 × 10–26 kgMoment of inertia, I = 1.94 × 10–46 kg m2Velocity of the oxygen molecule, v = 500 m/sThe separation between the two atoms of the oxygen molecule = 2R Mass of each oxygen atom = m/2Hence, moment of inertia I, is calculated as:(m/2)R2 + (m/2)r2 = mr2r = ( I / m)1/2(1.94 × 10-46 / 5.36 × 10-26 )1/2 = 0.60 × 10-10 mIt is given that:KErot = (2/3)KEtrans(1/2) I ω2 = (2/3) × (1/2) × mv2mr2ω2 = (2/3)mv2ω = (2/3)1/2 (v/r)= (2/3)1/2 (500 / 0.6 × 10-10) = 6.80 × 1012 rad/s. |
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