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Suppose the earth suddenly shrinks in size, still remaining spherical and mass unchanged (All gravitational forces pass through the centre of the earth).A. The days will become shorter.B. The kinetic energy of rotation about its own axis will decreaseC. The duration of the year will increaseD. The magnitude of angular momentum about its axis will increase. |
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Answer» Correct Answer - A `I_(1)omega_(1)=I_(2)omega_(2)` (Angular momentum is conserved) As `I_(2)` decreases `omega_(2)` increases. Thus `T=(2pi)/(omega)` i.e. `T` decreases Therefore the earth is completing each circle around its own axis in lesser time. `K.E.=1/2Iomega^(2)` Therefore `K.E.` of rotation increases. Duration of the year is dependent upon time taken to complete one revolution around the sun. |
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