7) An Ice skater with her arms extended is rotating with initial kinetic energy Eki and has a moment of inertia I, then when she pulls her arms close to her body her moment of inertia goes down to 0.25 I. The final total kinetic energy (Ekf ) of the skater is A. Eki B. 2Eki C. 4Eki D. 16Eki E. Eki/4

C. 4Eki

Explanation:

The kinetic energy due to the rotation is:

The motion of the ice skater is modelled after the Principle of Angular Momentum Conservation:

The initial angular speed is:

The final angular speed is:

The final kinetic energy is:

The correct answer is option C.

explanation: magnetic pole, region at each end of a magnet where the external magnetic field is strongest. the south-seeking pole, or any pole similar to it, is called a south magnetic pole. unlike poles of different magnets attract each other; like poles repel each other.