When the piston begins to travel downward in the cylinder, what occurs?

When the piston begins to travel downward in the cylinder, what occurs?

• A. Increases pressure
• B. Creates a vacuum
• C. Compresses air
• D. Ignites fuel

Answer: (B)

When the piston moves downward, the cylinder volume increases and the pressure inside the cylinder drops below the surrounding pressure, creating a vacuum. This vacuum pulls in air (and fuel in a gasoline engine) through the intake valve to fill the cylinder for the next cycle. The other events happen at different parts of the cycle: pressure rises during compression, air is compressed as the piston rises, and fuel is ignited later after compression.

When the piston moves downward, the cylinder volume increases and the pressure inside the cylinder drops below the surrounding pressure, creating a vacuum. This vacuum pulls in air (and fuel in a gasoline engine) through the intake valve to fill the cylinder for the next cycle. The other events happen at different parts of the cycle: pressure rises during compression, air is compressed as the piston rises, and fuel is ignited later after compression.