Question

A flywheel in a steam engine ensures a smooth ride for the passengers on the vehicle because it has

• A. low mass
• B. high speed
• C. low acceleration
• D. large moment of inertia
• E. high friction

Hint:

Think of a flywheel like a heavy spinning top. Because it is heavy and wide (high $I$), it is very hard to stop or speed up suddenly. This "rotational laziness" is exactly what smooths out the engine's power pulses.

Answer 1

The Correct Option is D

Concept:
Physics - Rotational Motion and Moment of Inertia.
Step 1: Understand the function of a flywheel.
A flywheel is a mechanical device specifically designed to efficiently store rotational energy. It acts as an energy reservoir, absorbing energy during periods where the power supply is greater than the load and releasing it when the load exceeds the supply.
Step 2: Analyze the role of Moment of Inertia.
Moment of Inertia ($I$) is the rotational analog of mass; it represents the resistance of an object to changes in its rotational motion. $$ \tau = I\alpha $$ where $\tau$ is torque and $\alpha$ is angular acceleration.
Step 3: Relate to smoothness of motion.
A large moment of inertia means that for a given fluctuating torque, the resulting change in angular velocity (angular acceleration) will be very small. This minimizes the "jerks" or fluctuations in speed, ensuring a steady and smooth rotation of the engine's shaft.
Step 4: Conclusion.
The flywheel's ability to maintain a constant speed despite fluctuating power strokes is due to its large moment of inertia.