In the given problem, the ceiling fan is rotating around a fixed axle, and the direction of angular velocity is along the axis of rotation, which is the z-axis.
Using the right-hand rule for angular velocity:
If the fan is rotating counterclockwise (when viewed from above), the direction of the angular velocity vector is along the positive z-axis.
If the fan is rotating clockwise (when viewed from above), the direction of the angular velocity vector is along the negative z-axis. Since the problem does not specify the direction of rotation, but typically, ceiling fans rotate counterclockwise when viewed from below, the direction of angular velocity is along the positive z-axis.
Thus, the correct answer is (D) \( -k \), assuming clockwise rotation.
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.
From a uniform disk of radius R, a circular hole of radius \(\frac{R}{2}\) is cut out. The centre of the hole is at \(\frac{R}{2}\) from the centre of the original disc. Locate the centre of gravity of the resulting flat body.
To maintain a rotor at a uniform angular speed of 200 rad s-1, an engine needs to transmit a torque of 180 N m. What is the power required by the engine ? (Note: uniform angular velocity in the absence of friction implies zero torque. In practice, applied torque is needed to counter frictional torque). Assume that the engine is 100% efficient.