1. Which of the following is a dimensional constant?
A.
Pi
B.
Gravitational constant
C.
Refractive index
D.
Strain
Correct Answer:
Gravitational constant
Explanation:
The gravitational constant has dimensions [M^-1 L^3 T^-2], so it is a dimensional constant.
2. What are the dimensions of the gravitational constant G?
A.
[M L T^-2]
B.
[M^-1 L^3 T^-2]
C.
[M L^2 T^-1]
D.
[M^0 L^0 T^0]
Correct Answer:
[M^-1 L^3 T^-2]
Explanation:
From F = Gm1m2/r^2, G = Fr^2/(m1m2), giving dimensions [M^-1 L^3 T^-2].
3. Which constant has the dimensions [M L^2 T^-1]?
A.
Speed of light
B.
Planck constant
C.
Gravitational constant
D.
Acceleration due to gravity
Correct Answer:
Planck constant
Explanation:
The Planck constant has dimensions of energy multiplied by time, which are [M L^2 T^-1].
4. The speed of light in vacuum is a dimensional constant. What are its dimensions?
A.
[L T^-1]
B.
[L T^-2]
C.
[M L T^-1]
D.
[M^0 L^0 T^0]
Correct Answer:
[L T^-1]
Explanation:
Speed is distance divided by time, so the speed of light has dimensions [L T^-1].
5. Which of the following is dimensionless rather than a dimensional constant?
A.
Planck constant
B.
Gravitational constant
C.
Speed of light
D.
Pi
Correct Answer:
Pi
Explanation:
Pi is a pure number and has dimensions [M^0 L^0 T^0], so it is dimensionless.
6. The dimensions of the universal gas constant R are the same as the dimensions of which quantity?
A.
Energy per mole per kelvin
B.
Force per unit area
C.
Mass per unit volume
D.
Length per unit time
Correct Answer:
Energy per mole per kelvin
Explanation:
From PV = nRT, R = PV/(nT), which is energy per mole per kelvin and is a dimensional constant.
7. Which of the following constants has dimensions [M L^2 T^-2]?
A.
Spring constant
B.
Energy per unit mass
C.
Surface tension
D.
Work or energy
Correct Answer:
Work or energy
Explanation:
Work or energy has dimensions force multiplied by distance, giving [M L^2 T^-2].
8. A dimensional constant is a physical constant that:
A.
Has no units
B.
Has dimensions and units
C.
Always has the value one
D.
Cannot be measured
Correct Answer:
Has dimensions and units
Explanation:
A dimensional constant possesses fixed dimensions and therefore has units that depend on the chosen system of measurement.
9. Which constant has the dimensions of acceleration?
A.
Gravitational constant G
B.
Acceleration due to gravity g
C.
Planck constant h
D.
Speed of light c
Correct Answer:
Acceleration due to gravity g
Explanation:
Acceleration due to gravity is a dimensional constant with dimensions [L T^-2].
10. If the unit system is changed, the numerical value of a dimensional constant generally:
A.
Changes
B.
Always becomes zero
C.
Remains one
D.
Loses its dimensions
Correct Answer:
Changes
Explanation:
The numerical value of a dimensional constant depends on the units used, although its physical meaning and dimensions remain unchanged.
Short questions are currently unavailable for this page.