WTMA Hydraulics and Fluid Dynamics 2 — Questions and Answers
Question 1: 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?
- 500 lbs (Correct answer)
- 250 lbs
- 100 lbs
- 1000 lbs
Correct answer: 500 lbs
Pascal's law: force scales with area ratio, so 50 × (20/2) = 500 lbs.
Question 2: 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?
- It quadruples (Correct answer)
- It doubles
- It stays the same
- It halves
Correct answer: It quadruples
Area decreases by a factor of 4 (diameter halved), so by continuity the velocity quadruples.
Question 3: Which property of a fluid describes its resistance to flow?
- Viscosity (Correct answer)
- Density
- Pressure
- Compressibility
Correct answer: Viscosity
Viscosity is the measure of a fluid's internal friction and resistance to flow.
Question 4: In a closed hydraulic system, if you increase pressure at one point, what happens throughout the system?
- Pressure increases equally everywhere (Correct answer)
- Only nearby areas see higher pressure
- Pressure drops downstream
- Pressure is absorbed by the fluid
Correct answer: Pressure increases equally everywhere
Pascal's principle states that pressure applied to an enclosed fluid is transmitted equally in all directions.
Question 5: 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?
- 5 gallons per minute (Correct answer)
- 10 gallons per minute
- 20 gallons per minute
- 2.5 gallons per minute
Correct answer: 5 gallons per minute
By continuity, total flow is conserved, so each equal branch carries half: 10/2 = 5 gpm.
Question 6: What does a pressure relief valve do in a hydraulic system?
- Limits maximum system pressure to prevent damage (Correct answer)
- Increases pressure when demand rises
- Filters contaminants from the fluid
- Converts pressure to flow
Correct 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.
Question 7: Bernoulli's principle states that in a flowing fluid, as velocity increases, pressure:
- Decreases (Correct answer)
- Increases
- Stays the same
- Becomes negative
Correct answer: Decreases
Bernoulli's principle shows an inverse relationship: higher velocity corresponds to lower pressure.
WTMA Hydraulics and Fluid Dynamics 2
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?