What is defined as a fluid resistance to flow?

What is defined as a fluid resistance to flow?

• A. Density
• B. Viscosity
• C. Pressure
• D. Turbulence

Answer: (B)

Viscosity is the property that describes a fluid’s resistance to flow. It comes from the internal friction between layers of the fluid—the thicker the fluid, the more those layers resist sliding past one another. That’s why honey pours slowly while water pours quickly: higher viscosity means more resistance to movement under the same force. In engines, viscosity matters because it governs how easily oil can circulate to lubricate bearings and surfaces. If the oil is too thick (high viscosity), it may not flow well at cold starts; if it’s too thin (low viscosity), it may not form a protective film at operating temperatures. Temperature also affects viscosity—the oil becomes less viscous as it heats up and more viscous as it cools down. Density is about mass per volume, pressure is force per area, and turbulence is a chaotic state of flow rather than a property that describes resistance to flow itself.

Viscosity is the property that describes a fluid’s resistance to flow. It comes from the internal friction between layers of the fluid—the thicker the fluid, the more those layers resist sliding past one another. That’s why honey pours slowly while water pours quickly: higher viscosity means more resistance to movement under the same force.

In engines, viscosity matters because it governs how easily oil can circulate to lubricate bearings and surfaces. If the oil is too thick (high viscosity), it may not flow well at cold starts; if it’s too thin (low viscosity), it may not form a protective film at operating temperatures. Temperature also affects viscosity—the oil becomes less viscous as it heats up and more viscous as it cools down.

Density is about mass per volume, pressure is force per area, and turbulence is a chaotic state of flow rather than a property that describes resistance to flow itself.