Physics Multiple Choice Questions on “Dimensional Analysis and its Applications”.
1. Identify the primary quantity from the following.
a) Mass
b) Density
c) Speed
d) Volume
Answer: a
Clarification: Mass is one of the 7 primary quantities in the SI system. Density is dependent on mass and volume. Speed is dependent on length and time. And volume is dependent on length as its cube.
2. Which of the following is a use of dimensional analysis?
a) To check the dimensional correctness of an equation
b) To solve the equation dimensionally
c) To get the number of dimensional constants
d) To understand the dimensional equation
Answer: a
Clarification: Dimensional analysis is basically used for two purposes. First, to check the dimensional correctness of an equation. Second, to convert a physical quantity from one system of units to another.
3. The dimension whose unit does not depend on any other dimension’s unit is known as ________
a) Fundamental dimension
b) Dependent dimension
c) Independent dimension
d) Absolute dimension
Answer: a
Clarification: A fundamental dimension is one, whose units do not depend on the units of any other dimension. There are 7 fundamental dimensions in the SI system and rest all are derived from them.
4. Which one of the following is a dimensionless quantity?
a) Mass
b) Weight
c) Specific weight
d) Reynold’s number
Answer: d
Clarification: Reynold’s number is a dimensionless quantity. Its formula is Re = ρvD/μ. On solving the associated dimensional equation, it will turn out that, Reynold’s number is dimensionless.