# Engineering Mechanics Questions and Answers – Fluid Pressure

«
»

This set of Engineering Mechanics Multiple Choice Questions & Answers (MCQs) focuses on “Fluid Pressure”.

1. The Pascal law states that liquid at rest applies pressure at a point is ________ in all directions.
a) Same
b) Un-same
c) Not matching
d) Matching but not equal

Explanation: The Pascal law states that the liquid at rest applies pressure at a point is the same in all directions. This means that the pressure is there in spite of the direction. And it is present in the same direction and is having the same magnitude.

2. Determine the location of the hydrostatic force acting on the submerged rectangular plate PaPb. Plate has a width of 1.5m. Density of water 1000kg/m3. a) 1.29m
b) 0.29m
c) 0.9m
d) 1.9m

Explanation: The Pascal law states that the liquid at rest applies pressure at a point is same in all directions. This means that the pressure is there in spite of the direction. And it is present in the same direction and is having same magnitude.

3. The magnitude of the pressure of the fluid is not dependent on the _________
a) Force
b) Area
c) Specific Weight
d) Temperature

Explanation: The Pascal law states that the liquid at rest applies pressure at a point is the same in all directions. This means that the pressure is there in spite of the direction. And it is present in the same direction and is having the same magnitude.

4. The Pascal’s law is applicable to the liquid which is __________________
a) Compressible
b) In-compressible
c) Solid in phase
d) Super-compressive

Explanation: The liquid must be incompressible. The Pascal law states that the liquid at rest applies pressure at a point is same in all directions. This means that the pressure is there in spite of the direction.

5. Gases are ________________ fluids.
a) Compressible
b) In-compressible
c) Solid in phase
d) Super-compressive

Explanation: The liquid must be incompressible. The Pascal law states that the liquid at rest applies pressure at a point is same in all directions. This means that the pressure is there in spite of the direction. But the gases are compressive that’s why it is not used in the gas form.

6. Pressure acts _____________ to the surface of the body.
a) Normal
b) Linear
c) Parallel
d) Coplanar

Explanation: The pressure is always acted normal to the surface of the body. Thus the pressure plays a role as a vector in this case. So mainly the pressure must be considered as normal to the surface of the body.

7. For the determination of the fluid pressure the body to be experimented is ___________ in the liquid.
a) Immersed
b) Non-immersed
c) Parallel
d) Normal

Explanation: The body used in the determination of the fluid pressure equations is immersed in the liquid. It is completely immersed in the liquid. So as to make the calculations of the pressure beneath the liquid.

8. What is a collinear system of forces for the system of the fluid liquids?
a) The force system having all the forces parallel to each other
b) The force system having all the forces perpendicular to each other
c) The force system having all the forces emerging from a single point
d) Forces cannot form a collinear system of forces, it is not possible

Explanation: The force system having all the forces emerging from a point is called the collinear system of force. This is a type of system of the force, which is easy in the simplification. This is because as the forces are the vector quantity, the vector math is applied and the simplification is done.

9. The system of the collinear and the parallel force for the calculations of the equations in the determination of the fluid pressure are simplified as ________________
a) The simplified collinear force system gives us a net force and the parallel force system gives us a simplified force, and then we add it vectorially
b) Such simplification is not possible
c) The simplification is usually done by not considering the directions of the both
d) The simplification is done by considering the rotations only

Explanation: The simplification is easy. The simplified force system gives us a net force and the parallel force system gives us a simplified force, and then we add it vectorially. Thus the vector addition at the last can be easily done and thus both can be simplified.

10. What is not the condition for the equilibrium in the determination of the equations of the fluid pressures?
a) ∑Fx=0
b) ∑Fy=0
c) ∑Fz=0
d) ∑F≠0

Explanation: For the equilibrium in the three dimensional system of axis we have all the conditions true as, ∑Fx=0, ∑Fy=0 and ∑Fz=0. Also, we have the summation of the forces equal to zero. Which is not a non-zero value.

11. If solving the question in 3D calculations is difficult, then use the 2D system to determine the equations of the fluid pressure.
a) True
b) False

Explanation: The answer is obviously yes. If we are having any difficulty in making the vector components, then we can go in 2D. As if the particle is in equilibrium, the net force will be zero. No matter where you see first. Net force is zero.

12. When the body is in equilibrium beneath the liquid then which of the following is true?
a) We equate all the components of the forces acting on the body equal to their resultant vector’s magnitude
b) We equate all the components of the forces acting on the body equal to their resultant vector’s magnitude square
c) We equate all the components of the forces acting on the body equal to their resultant vector’s magnitude square root
d) We equate all the components of the forces acting on the body equal to zero

Explanation: Yes, we equate all the components of the three axis equal to zero. That is the resultant of the forces along the three axis are being equated to zero. This brings in that there is no net force along any direction. Hence equilibrium.

13. We first make equilibrium equations for the fluid pressure and then the free body diagram and then solve the question?
a) True
b) False

Explanation: We first make the free body diagram and then we make the equilibrium equations to satisfy the given conditions. This helps us to solve the question easily. As this reduces the part of imagination and increases accuracy too.

14. ∑Fx=0, ∑Fy=0 and ∑Fz=0 are vector equations for the determination of the equilibrium equations for the fluid pressure in the body immersed in the liquid.
a) True
b) False

Explanation: The answer is false as the equations asked are scalars. As we make the net sum of the forces along the axis equal to zero. Of course this equation comes from the solving the vector forms, but still, the result is a scalar, hence the equations are scalar.

15. Determine the resultant hydrostatic force acting on the submerged rectangular plate PaPb. Plate has width of 1.5m. Density of water 1000kg/m3. a) 154.5 kN/m
b) 54.5 kN/m
c) 14.5 kN/m
d) 112.5 kN/m  