An airplane propeller rotating at 1200 rpm has 2600 j of kinetic energy. what is its rotational inertia?

Moment of Inertia:

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The angular velocity is in rpm or rotations per minutes. In SI units, the unit should reads radians per second. Each rotation is radians and there are sixty seconds in one minute. Convert to SI units:

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"Radian" is implied and isn't shown in the unit.

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no. dot product   =0 when vecs at right angles

i already answered it by 34/s