# Fluid Mechanics Questions and Answers – Rayleighs Method

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

1. What is the mathematical technique used to predict physical parameters?
a) Combustion analysis
b) Pressure analysis
c) Dimensional analysis
d) Temperature analysis

Explanation: Dimensional analysis is a process which is used to determine physical parameters that influence the fluid flow. The analysis is based on the fundamental units. The fundamental units are mass, length and time.

2. Which among the following method is used to find a functional relationship with respect to a parameter?
a) Rayleigh’s method
b) Rutherford’s method
c) Newton’s laws
d) Doppler effect

Explanation: Rayleigh’s method is a basic method for finding the functional relationship. The functional relationship is found with respect to a physical parameter. It is illustrated using the MLT system.

3. Which among the following is not the correct symbol?
a) Size- l
b) Velocity – v
c) Gravity – g
d) Viscosity – a

Explanation: The symbol used for viscosity is false. Viscosity is denoted by the symbol ‘µ’ (Mew). It is defined as the resistance to flow of fluid. Resistance takes place as one layer of fluid slides over the other.

4. Which among the following is the correct format for Rayleigh’s method?
a) D = f(l,ρ,μV,g)
b) D = (l,ρ,μV,g)
c) D = f
d) D = f(lpv)

Explanation: The correct format for Rayleigh’s method is D = f(l,ρ,μV,g). Where, D is the dimensional analysis, ‘f’ is the function, and the variables inside the bracket are the physical parameters to determine the function.

5. What does ‘C’ denote in D = ClaρbμcVdge?
a) Function
b) Dimensions
c) Dimensionless constant
d) Number of parameters

Explanation: ‘C’ in D = ClaρbμcVdge denotes dimensionless constant and a,b,c,d,e, are its exponents. This is the fundamental purpose of Rayleigh’s method.
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6. Why does Rayleigh’s method have limitations?
a) To many variables
b) Format
c) Exponents in between variables
d) Many exponents

Explanation: The main limitation of the Rayleigh’s method is that it has exponential relationship between the variables. It makes it more complex for solving. Since, more variables with exponents will lead to a confusion in the solving process.

7. Which among the following is same as the Rayleigh’s method?
a) Buckingham method
c) Conveyor method
d) Ionization method

Explanation: Buckingham method is also called as the ‘pi’ theorem method. This method can be illustrated by various moving components. It plays an important role in finding the drag of various moving objects.

8. Which among the following is not a dimensionless number?
a) Reynolds
b) Froude
c) Mach
d) Cartesian

Explanation: Dimensionless numbers are numbers with a dimension of one. It is a pure number. It does not contain any physical unit. No change takes place due to altering of any variable.

Sanfoundry Global Education & Learning Series – Fluid Mechanics.