An engine requires a rotating mass to build _________ to keep it running between power pulses.

An engine requires a rotating mass to build _________ to keep it running between power pulses.

• A. Pressure
• B. Speed
• C. Friction
• D. Inertia

Answer: (D)

The concept here is inertia and how a rotating mass, like a flywheel, smooths engine operation. A flywheel stores energy in the form of kinetic energy, which comes from its inertia—the resistance to any change in its motion. As the engine fires and produces torque in bursts, the flywheel absorbs some of that energy and then releases it during the gaps between power pulses. This keeps the crankshaft turning at a steadier rate and helps maintain continuous engine operation. Pressure isn’t something a rotating mass builds to keep the engine running; it’s a different force concept altogether. Speed is the motion you’re trying to maintain, not what the rotating mass primarily stores to bridge gaps. Friction would oppose motion and dissipate energy, making it harder to keep spinning, not easier. Inertia, the stored kinetic energy in the rotating mass, is exactly what provides the smooth continuation of motion between power events.

The concept here is inertia and how a rotating mass, like a flywheel, smooths engine operation. A flywheel stores energy in the form of kinetic energy, which comes from its inertia—the resistance to any change in its motion. As the engine fires and produces torque in bursts, the flywheel absorbs some of that energy and then releases it during the gaps between power pulses. This keeps the crankshaft turning at a steadier rate and helps maintain continuous engine operation.

Pressure isn’t something a rotating mass builds to keep the engine running; it’s a different force concept altogether. Speed is the motion you’re trying to maintain, not what the rotating mass primarily stores to bridge gaps. Friction would oppose motion and dissipate energy, making it harder to keep spinning, not easier. Inertia, the stored kinetic energy in the rotating mass, is exactly what provides the smooth continuation of motion between power events.