Hydraulics and Fluid Dynamics Flashcards

A hydraulic jack uses a small piston with area 2 sq in and a large piston with area 20 sq in. If you apply 50 lbs on the small piston, what force does the large piston exert?

Answer: 500 lbs

Pascal's law: force scales with area ratio, so 50 × (20/2) = 500 lbs.

Water flows through a pipe that narrows from 4 inches to 2 inches in diameter. What happens to the flow velocity in the narrow section?

Answer: It quadruples

Area decreases by a factor of 4 (diameter halved), so by continuity the velocity quadruples.

Which property of a fluid describes its resistance to flow?

Answer: Viscosity

Viscosity is the measure of a fluid's internal friction and resistance to flow.

In a closed hydraulic system, if you increase pressure at one point, what happens throughout the system?

Answer: Pressure increases equally everywhere

Pascal's principle states that pressure applied to an enclosed fluid is transmitted equally in all directions.

A pipe carries oil at 10 gallons per minute through a 2-inch diameter section. The pipe then splits into two equal branches. How much flow goes through each branch?

Answer: 5 gallons per minute

By continuity, total flow is conserved, so each equal branch carries half: 10/2 = 5 gpm.

What does a pressure relief valve do in a hydraulic system?

Answer: Limits maximum system pressure to prevent damage

A relief valve opens at a set pressure to divert fluid and protect components from over-pressure.

Bernoulli's principle states that in a flowing fluid, as velocity increases, pressure:

Answer: Decreases

Bernoulli's principle shows an inverse relationship: higher velocity corresponds to lower pressure.