Test: Introduction to Fluid Mechanics - Mechanical Engineering MCQ

Explanation: Ideal fluids haze zero surface tension but real fluids have some finite value of surface tension.

Explanation: A fluid is a Tresca material with zero cohesion. In simple words, fluid is in a state of failure.

Correct option is A.
A fluid that has no resistance to shear stress between its layers is known as an ideal fluid. Hence ideal fluid  has zero viscosity.

Explanation: Fluids (liquids and gases) cannot resist even a small shear force and gets permanently deformed. Hence, the element must be a solid element.

Explanation: Solid molecules have a definite shape due to large inter-molecular forces. In liquids, molecules are free to move inside the whole mass but rarely escape from itself. Thus, liquids can form free surfaces under the effect of gravity. But, in case of gases, molecules tend to escape due to low forces of attraction. Thus, gases won’t form any free surface.

Explanation: Fluid Mechanics deals with the study of fluid at rest or in motion with or without the consideration of forces, Fluid Statics is the study of fluid at rest, Fluid Kinematics is the study of fluid in motion without consideration of forces and Fluid Dynamics is the study of fluid in motion considering the application forces.

Ideal fluids are incompressible which means they will have zero compressibility.

Explanation: Bulk modulus k is the reciprocal of compressibility fi.
k = ¹⁄_fi
Ideal fluids are incompressible which means fi = 0. Thus, k will be infinity.

A fluid is defined as a substance that deforms continuously whilst acted upon by any forcetangential to the area on which it acts. Such a force is termedashear force, and theratio of the shear force to the area on which it acts is known astheshear stress

When a fluid is at rest neither shear forces nor shear stresses exist in it.

Difference in pressure across an air bubble

Let pressure at that point is ‘p’ (absolute)
The pressure above the (1) – (1) will be equal. So

P (gauge )=1236.06 Pa

Therefore Correct Answer is (a)

Let the density of the body be 

Hence the correct answer is 865 kg/m³.

Bulk modulus of elasticity of oil

Hence, the correct option is (b).

PA = −50 cm Hg (Vacuum)
Patm = 76 cm Hg (abs)
O = (gauge)

So, Patm = P_A + Pressure due to column Hg of height ‘H’
O = −50 + H; H = 50 cm Hg

Hence Correct Answer is Option (b)