Heat Transfer MCQ’s – Buckingham’s Pi- Method
1 - Question
f there are n variables in a dimensionally homogeneous equation and if these variables contain m primary dimensions, then the variables can be grouped into how many non-dimensional parameters?
Explanation: The non-dimensional groups are called pi-terms. If there are n variables in a dimensionally homogenous equation and if these variables contain m primary dimensions, then the variables can be grouped into (n – m) non dimensional parameters.
2 - Question
Which of the following is not known as a core group?
b) Geometric property
c) Fluid property
d) Flow characteristics
Explanation: These are also known as repeated variables.
3 - Question
What is the dimension of resistance?
a) M L T 2
b) M L T
c) M L T -2
d) M L T -1
Explanation: Unit of resistance is N. Resistance is the stopping effect exerted by one material thing to another.
4 - Question
he resistance R experienced by a partially submerged body depends upon the velocity V, length of the body l, viscosity of the fluid µ, density of the fluid p and gravitational acceleration g. Establish a relation between involving non-dimensional groups
a) R = p V l 2 function [p V l/ µ, V/ (lg) 1/2].
b) R = p l 2 function [p V l/ µ, V/ (lg) 1/2].
c) R = V 2 l 2 function [p V l/ µ, V/ (lg) 1/2].
d) R = p V 2 l function [p V l/ µ, V/ (lg) 1/2].
Explanation: This can be solved by Buckingham pi theorem.
5 - Question
If there are 6 physical quantities and 3 fundamental units, then the number of pi terms are
Explanation: It should be 6-3 = 3.
6 - Question
The study of predicting prototype conditions from model observations is known as
b) Geometrical similarity
Explanation: It prescribes the relationship between a full scale flow and a flow involving smaller but geometrically similar boundaries.
7 - Question
S.I unit of heat is
c) J s
Explanation: Its unit is Joule. Heat is a form of energy that can be transferred between two objects.
8 - Question
S.I unit of the coefficient of volumetric expansion is
b) Per meter
c) Per second
d) Per degree
Explanation: Its unit is per degree. Coefficient of volumetric expansion is defined as increase in volume.
9 - Question
S.I unit of specific heat is
a) K kg/J
c) k J/kg K
Explanation: Its unit is k J/kg K. It is another physical property of matter. All the matter has a temperature associated with it.
10 - Question
S.I unit of dynamic viscosity is
b) kg/m s
d) m s /kg
Explanation: Its unit is kg/m s. It is the kinematic viscosity per unit density.