The correct answer is C) both (a) and (b).

Why Multi-Cylinder Engines are Desirable and How They Reduce Balancing Problems and Flywheel Size:

Multi-cylinder engines, such as those found in most automobiles, are preferred over single-cylinder engines for several reasons, including their ability to address balancing problems and reduce the size of the flywheel. Here’s a detailed explanation of why both (a) and (b) are correct:

A. Balancing Problems are Reduced:

Balancing is a critical aspect of engine design. Engines generate reciprocating and rotating forces as pistons move up and down and the crankshaft rotates. These forces can result in vibrations and oscillations that, if not properly balanced, can lead to engine inefficiency, increased wear and tear, and discomfort for passengers in the case of vehicles.

In a multi-cylinder engine, the presence of multiple cylinders and pistons working in a coordinated manner naturally helps in reducing balancing problems. The arrangement of cylinders in a specific firing order and the overlapping of power strokes ensure that the engine generates smoother and more balanced power output.

By distributing the workload among multiple cylinders, the engine can offset the forces generated during each piston’s movement, reducing vibrations and improving overall engine balance. This results in a more comfortable and efficient engine operation.

B. Flywheel Size is Reduced:

A flywheel is a mechanical device used in engines to store and smooth out kinetic energy. It is especially important in single-cylinder engines to ensure a continuous and stable power output throughout the engine’s rotation cycle.

In multi-cylinder engines, the inherent balance achieved through multiple cylinders and pistons working in tandem reduces the need for a large and heavy flywheel. Because the engine naturally generates more even power delivery, there is less need for additional mass to stabilize engine operation.

This reduction in flywheel size is advantageous for several reasons. It results in a lighter engine, which contributes to improved fuel efficiency, faster engine response, and reduced overall vehicle weight. Lighter flywheels also enhance engine revving characteristics, making the engine more responsive to throttle inputs.

Why the Other Options are Not Correct:

A. Only Balancing Problems are Reduced:

This option implies that the primary benefit of multi-cylinder engines is the reduction of balancing problems. While balancing is indeed one of the benefits, it’s not the only advantage. Multi-cylinder engines offer a range of advantages, including improved power output, smoother operation, and reduced flywheel size, as explained above.

B. Only Flywheel Size is Reduced:

Similarly, this option suggests that the sole advantage of multi-cylinder engines is the reduction in flywheel size. While this is a significant benefit, multi-cylinder engines offer more advantages, including better balancing, increased power, and smoother operation.

D. None of the Mentioned:

This option is incorrect because, as detailed above, multi-cylinder engines do provide benefits, including the reduction of balancing problems and flywheel size. Therefore, the correct answer is not “none of the mentioned.”

In summary, multi-cylinder engines are desirable for various reasons, including their ability to reduce balancing problems and the need for large flywheels.

They achieve smoother and more efficient engine operation, making them the preferred choice for a wide range of applications, from automobiles to industrial machinery. Both (a) and (b) correctly capture some of the key advantages of multi-cylinder engines.