Hydrostatics

Question 1

1. Hydrostatics deals with fluids that are ___.
   A. In motion B. At rest C. Under turbulence D. Flowing steadily

Answer 1

✅ Answer: B – At rest
No shear stress acts when fluid is stationary.

Question 2

2. The pressure intensity at a point in a static fluid is equal in ___.
   A. Vertical direction only B. Horizontal direction only C. All directions D. No direction

Answer 2

✅ Answer: C – All directions
Pascal’s Law — pressure is same in all directions at a point.

Question 3

3. The absolute pressure is equal to ___.
   A. Gauge + Atmospheric B. Gauge – Atmospheric C. Static + Dynamic D. None of these

Answer 3

✅ Answer: A – Gauge pressure + Atmospheric pressure
Pabs = Pg + Patm.

Question 4

4. The pressure at a depth h below the free surface is ___.
   A. γh B. ρh C. h/ρ D. P/γ

Answer 4

✅ Answer: A – γh
γ = specific weight = ρg.

Question 5

5. The SI unit of pressure is ___.
   A. bar B. atm C. Pascal D. psi

Answer 5

✅ Answer: C – Pascal
1 Pa = 1 N/m².

Question 6

6. Pressure at the same level in a continuous static fluid is ___.
   A. Different B. Equal C. Zero D. Maximum

Answer 6

✅ Answer: B – Equal
For same fluid in same plane, pressure is same.

Question 7

7. The free surface of a liquid at rest is always ___.
   A. Parallel to container bottom B. Inclined C. Perpendicular to gravity D. Horizontal and level

Answer 7

✅ Answer: D – Horizontal and level
Gravity causes equal potential at surface.

Question 8

8. The pressure difference between two points in a liquid column is due to ___.
   A. Surface tension B. Viscosity C. Weight of liquid D. Capillarity

Answer 8

✅ Answer: C – Weight of liquid
ΔP = γh, pressure increases with depth.

Question 9

9. A manometer is used to measure ___.
   A. Temperature B. Flow C. Pressure D. Density

Answer 9

✅ Answer: C – Pressure
Based on balancing liquid columns.

Question 10

10. The pressure at a depth of 5 m in water (γ = 9.81 kN/m³) is ___.
    A. 19.6 kPa B. 29.4 kPa C. 39.2 kPa D. 49.1 kPa

Answer 10

✅ Answer: D – 49.1 kPa
P = γh = 9.81 × 5 = 49.05 kPa.

Question 11

11. For two points A and B in same horizontal plane of a static fluid, pressure difference is ___.
    A. γ(hA – hB) B. Zero C. ρg(hA – hB) D. Depends on viscosity

Answer 11

✅ Answer: B – Zero
Equal elevation → equal pressure.

Question 12

12. The pressure at the bottom of a tank depends on ___.
    A. Area of base B. Shape of tank C. Depth of liquid D. Type of liquid only

Answer 12

✅ Answer: C – Depth of liquid
Pascal’s Law → independent of area or shape.

Question 13

13. The total pressure on a vertical plane surface submerged in a liquid acts at ___.
    A. Centroid B. Center of Gravity C. Center of Pressure D. Mid-depth

Answer 13

✅ Answer: C – Center of Pressure
It’s below centroid due to pressure increase with depth.

Question 14

14. Depth of center of pressure (h_cp) for vertical plane = ___.
    A. h̄ B. h̄ + (I_G / A h̄) C. h̄ – (I_G / A h̄) D. h̄ × γ

Answer 14

✅ Answer: B – h̄ + (I_G / A h̄)
Derived from moment of pressure distribution.

Question 15

15. Pressure head = ___.
    A. P / γ B. γ / P C. P × h D. ρgh

Answer 15

✅ Answer: A – P / γ
Height equivalent to pressure.

Question 16

16. A U-tube differential manometer measures ___.
    A. Pressure difference between two points B. Absolute pressure C. Atmospheric pressure D. Flow rate

Answer 16

✅ Answer: A – Pressure difference between two points
Uses two columns connected to fluid lines.

Question 17

17. Gauge pressure at a point where Pabs = 120 kPa and Patm = 100 kPa is ___.
    A. 20 kPa B. 120 kPa C. 100 kPa D. –20 kPa

Answer 17

✅ Answer: A – 20 kPa
Pg = Pabs – Patm.

Question 18

18. Pressure head corresponding to 100 kPa in water is ___.
    A. 5.0 m B. 7.65 m C. 10.2 m D. 20 m

Answer 18

✅ Answer: C – 10.2 m
h = P/γ = 100,000 / 9,810 = 10.2 m.

Question 19

19. The resultant pressure on a plane surface = ___.
    A. Average pressure × area B. Centroid pressure C. γh × A D. I_G / h̄

Answer 19

✅ Answer: A – Average pressure × area
Total pressure = intensity × area.

Question 20

20. The center of pressure of a rectangle immersed vertically is always ___.
    A. At centroid B. Above centroid C. Below centroid D. Midpoint

Answer 20

✅ Answer: C – Below centroid
Because pressure increases with depth.

Question 21

21. The pressure at the free surface of a liquid open to atmosphere is ___.
    A. 0 (gauge) B. 1 atm absolute C. 101.3 kPa gauge D. Depends on fluid

Answer 21

✅ Answer: A – 0 gauge pressure
Atmospheric acts as reference zero gauge.

Question 22

22. Pascal’s Law states that ___.
    A. Pressure acts upward only B. Pressure applied at any point is transmitted undiminished in all directions C. Pressure decreases with area D. None of these

Answer 22

✅ Answer: B – Pressure transmitted undiminished in all directions
Basis for hydraulic press and jacks.

Question 23

23. A piezometer measures ___.
    A. Static pressure B. Dynamic pressure C. Differential pressure D. Flow velocity

Answer 23

✅ Answer: A – Static pressure
Simple open-tube device for low pressures.

Question 24

24. If a tank is open to atmosphere, absolute pressure at 3 m below surface = ___.
    A. 29.43 kPa B. 30.0 kPa C. 100 + 29.43 = 129.43 kPa D. 9.81 × 3 = 19.6 kPa

Answer 24

✅ Answer: C – 129.43 kPa
Add atmospheric pressure to gauge value.

Question 25

25. Hydraulic machines like press or lift are based on ___. A. Archimedes’ Principle B. Bernoulli’s Theorem C. Pascal’s Law D. Continuity Equation

Answer 25

✅ Answer: C – Pascal’s Law Equal transmission of pressure amplifies force.