Final answer:
Increasing the number of blades on a propeller leads to an increase in the moment of inertia because there is more mass further away from the axis of rotation, making it harder to change the rotational motion of the propeller. The correct answer is A) Yes, directly.
Step-by-step explanation:
Increasing the number of blades on a propeller does indeed increase the moment of inertia. The moment of inertia is a quantity that measures how hard it is to change the rotational motion of an object. With more blades, there is more mass distributed further from the axis of rotation, which raises the moment of inertia.
Looking at basic physics principles, the moment of inertia, I, for a point mass is calculated as I = mr², where m is the mass and r is the distance from the axis of rotation. For a propeller, each additional blade can be thought of as additional point masses placed at a certain distance from the rotational axis.
Thus, increasing the number of blades directly increases the moment of inertia because the mass (m) is effectively increased, and the distribution of this mass from the axis (r) also becomes more significant.
Using examples to explain, consider a simple case where a propeller has two blades and then is modified to have four blades.
Assuming the extra blades are identical and positioned evenly, the propeller with four blades has double the mass distributed at the same radii as the original two-blade design, leading to a direct increase in moment of inertia.
It's important to note that this increase in the moment of inertia would make the propeller harder to start or stop spinning, which is a key consideration in designing propulsion systems.