Fluid Mechanics
Hydrostatics
Questions and Answers
1. For the tank shown in Fig. (1), find the pressure in KPa, at points A, B, C, and
D.
2. In Fig. (2), the pressure gauge A in the tank shown reads 1.5 KPa (gauge). Find
the elevations of the liquid levels in the open piezometer tubes B and C.
3. For the pipes shown in Fig. (3), Find the absolute and gauge pressures at
the center of pipe A in N / m 2. Find the pressure head in the pipe as a
meters of water.
4. Calculate the pressure difference between pipes A and B in the setup shown
in Fig. (4).
5. A 6 m wide gate AB in Fig. (5) weighs 2 tons. As shown it is hinged at B and
rests against a smooth wall at A. Find the water level h at which the gate will
start to open.
6. For the gate shown in Fig. (6) find the minimum value of Z for which the will
rotates counterclockwise if the gate is (a) rectangular, 1.2 by 1.2 m; (b)
triangular, 1.2 m base as axis, height 1.2 m.
7. (a) A circular butterfly gate revolved about a horizontal axis passing through its
centroid is subjected to hydrostatic thrust on one side and counterbalanced by a
force F, applied at the bottom as shown in Fig. (7). If the diameter of the gate is
4 m and the water depth is 1 m above the gate. Find the force F, required to keep
the gate in position.
(b) If the gate is to retain water to its top level on the other side also, find the net
hydrostatic thrust on the gate and propose the new condition for the gate to be in
equilibrium.
8. The Tainter gate in Fig. (8), has a cylindrical surface of radius 10 m and is
supported by a framework hinged at its center. Determine the magnitude and
direction of the resultant hydrostatic thrust force affecting the gate.
9. The profile of the inner face of a dam is a parabola with equation; y = 0.30 x 2
(as shown in. Fig. (9)). The dam holds water to a depth of 30 m above the base.
Find the hydrostatic thrust on the dam per unit length, its inclination to the
vertical and the point at which the line of action of this thrust intersects the
horizontal base of the dam.
, 10. Calculate the magnitude and location of the resultant force on the
circular arc shownin Fig. (10) for the following two case:
a. Pg=120.11 KPa abs
b. Pg=90.68 KPa abs
The arc is 25 m long (normal to the paper)
11. The cylinder shown in Fig.11 retains oil and water. Find the resultant
hydrostatic thrust force on the cylinder per unit length and its inclination to the
vertical.
12. The log shown in Fig.12 retains oil from a side and water from the other side.
Find the resultant hydrostatic thrust force pushing the log against the wallper unit
length. Also find the specific gravity of the log material. Assuming the re action
of the wall is normal to the log surface.
13. A steel pipe 1.2m diameter carrying oil of S.G.=0.90. A pressure head of 5.8
m of mercury was measured at a point on the pipeline. If the allowable stress of
the steel is 1800 kg / cm2, find the thickness of the pipe wall.
Hydrostatics
Questions and Answers
1. For the tank shown in Fig. (1), find the pressure in KPa, at points A, B, C, and
D.
2. In Fig. (2), the pressure gauge A in the tank shown reads 1.5 KPa (gauge). Find
the elevations of the liquid levels in the open piezometer tubes B and C.
3. For the pipes shown in Fig. (3), Find the absolute and gauge pressures at
the center of pipe A in N / m 2. Find the pressure head in the pipe as a
meters of water.
4. Calculate the pressure difference between pipes A and B in the setup shown
in Fig. (4).
5. A 6 m wide gate AB in Fig. (5) weighs 2 tons. As shown it is hinged at B and
rests against a smooth wall at A. Find the water level h at which the gate will
start to open.
6. For the gate shown in Fig. (6) find the minimum value of Z for which the will
rotates counterclockwise if the gate is (a) rectangular, 1.2 by 1.2 m; (b)
triangular, 1.2 m base as axis, height 1.2 m.
7. (a) A circular butterfly gate revolved about a horizontal axis passing through its
centroid is subjected to hydrostatic thrust on one side and counterbalanced by a
force F, applied at the bottom as shown in Fig. (7). If the diameter of the gate is
4 m and the water depth is 1 m above the gate. Find the force F, required to keep
the gate in position.
(b) If the gate is to retain water to its top level on the other side also, find the net
hydrostatic thrust on the gate and propose the new condition for the gate to be in
equilibrium.
8. The Tainter gate in Fig. (8), has a cylindrical surface of radius 10 m and is
supported by a framework hinged at its center. Determine the magnitude and
direction of the resultant hydrostatic thrust force affecting the gate.
9. The profile of the inner face of a dam is a parabola with equation; y = 0.30 x 2
(as shown in. Fig. (9)). The dam holds water to a depth of 30 m above the base.
Find the hydrostatic thrust on the dam per unit length, its inclination to the
vertical and the point at which the line of action of this thrust intersects the
horizontal base of the dam.
, 10. Calculate the magnitude and location of the resultant force on the
circular arc shownin Fig. (10) for the following two case:
a. Pg=120.11 KPa abs
b. Pg=90.68 KPa abs
The arc is 25 m long (normal to the paper)
11. The cylinder shown in Fig.11 retains oil and water. Find the resultant
hydrostatic thrust force on the cylinder per unit length and its inclination to the
vertical.
12. The log shown in Fig.12 retains oil from a side and water from the other side.
Find the resultant hydrostatic thrust force pushing the log against the wallper unit
length. Also find the specific gravity of the log material. Assuming the re action
of the wall is normal to the log surface.
13. A steel pipe 1.2m diameter carrying oil of S.G.=0.90. A pressure head of 5.8
m of mercury was measured at a point on the pipeline. If the allowable stress of
the steel is 1800 kg / cm2, find the thickness of the pipe wall.
