Units and Measurements

Question 1

What is the Conversion/Relational formula for C° and F° ??

Answer 1

C°/5 = (F° - 32)/9

Question 2

Speed of light in vacuum?

Answer 2

3 × 10^8 m/s

Question 3

Fundamental physical quantities?

Answer 3

Mass (kg)
Length (m)
Time (s)
Current (A)
Temprature (K)
Amount of Substance (Mol)
Luminous Intensity (Cd.)

Question 4

Classification of PQs on basis of direction is Vector and Scalar. What is a hidden factor (law) in determining this classification?

Answer 4

Addition. Ex- Current has direction but is scalar. Addition of current doesn’t depends on direction. This is known as ‘Law of Scalar Additon’.

Question 5

Define unit.

Answer 5

Standard reference unit of any PQ.

Question 6

Name 4 Sets of Units.

Answer 6

MKS (m,kg,s)
CGS (cm,g,s)
FPS (foot,pound,s)
SI (m,kgs,s)

Question 7

What differentiates MKS set of units from SI set of units?

Answer 7

SI = MKS + Supplementary units

Supplementary Units = Angle and Solid Angle

Question 8

Name relation between degree and radian.

Answer 8

360° = 2π radians
180° = π radians
1° = π/180 radians

Question 9

Name relations between degree, radian, minute and second.

Answer 9

1° = π/180 radians
1° = 60’ or 60 mins
1’ = 60” or 60 secs

Question 10

Name relation between degree, radian, minute and second.

Answer 10

1° = π/180 radians
1° = 60’ or 60 mins
1’ = 60” or 60 secs

Question 11

Length of 1 Light Year?

Answer 11

9.46 × 10^15 m
(Distance travelled by light in one year)

Question 12

Length of 1 Astronomical Unit (AU)

Answer 12

1.5 × 10^11m
(Avg. Distance between Earth and Sun)

Question 13

Length of 1 Parsec ?

Answer 13

3 × 10^16 m
It is radius of an arc whose arclength is 1 astronomical unit (1 AU), the angle then formed at the centre is 1 second (1”).

Question 14

Arrange Parsec, AU and Light Year in ascending order.

Answer 14

1 Parsec > 1 LY > 1 AU

Question 15

Name metric prefixes in order.

Answer 15

Tera (10^12)
Giga (10^9)
Mega (10^6)

Kilo (10^3)
Hecta (10^2)
Deca (10^1)
Meter (1)
Deci (10^-1)
Centi (10^-2)
Milli (10^-3)

Micro (10^-6)
Nano (10^-9)
Pico (10^-12)
Famto (Fermi) (10^-15)

1 Å (Angstrom) = 10^-10m.

Question 16

When we convert PQs, nu is ___?
Where n and u are?
How are their graphs formed?

Answer 16

Constant.
Experimental reading = nu where n = magnitude and u = unit.
n to u forms curve towards downwards graph.
nu to n or u forms straight line graph not touching x axis.

Question 17

Dimension of Radius of Gyration?

Answer 17

L

Question 18

Dimension of wavelength?

Answer 18

L

Question 19

Dimension of Focal Length?

Answer 19

L

Question 20

Dimension of Parsec?

Answer 20

L

Question 21

Dimension of Relative Velocity?

Answer 21

LT^-1

Question 22

Average Speed’s Dimension is?

Answer 22

LT-1

Question 23

Orbital and Critical Velocity have same dimension and play some parts in orbitals. What is their dimension?

Answer 23

LT-1

Question 24

Intensity of Gravitional Field has the dimension…

Answer 24

LT-2

Question 25

Centripetal Acceleration has the dimension…..

Answer 25

LT-2

Question 26

Avg. Acceleration has the dimension…

Answer 26

LT-2

Question 27

Acceleration due to Gravity has the dimension..

Answer 27

LT-2

Question 28

Dimension of Momentum?

Answer 28

MLT-1

Question 29

Power has the dimension…

Answer 29

ML2T-3

Question 30

Angular Momentum has the dimension…..

Answer 30

ML2T-1

Question 31

Dimension of Impulse

Answer 31

MLT-1

Question 32

Dimension of Impulse?

Answer 32

MLT-1

Question 33

Thrust has the dimension…

Answer 33

MLT-2

Question 34

Viscous Drag has the dimension…

Answer 34

MLT-2

Question 35

Tension’s Dimension?

Answer 35

MLT-2

Question 36

Weight has the dimension?

Answer 36

MLT-2

Question 37

Radiation and Magnetism have the dimension?

Answer 37

MLT-2

Question 38

Dimension of Gravitation?

Answer 38

MLT-2

Question 39

Buoyancy has the dimension…

Answer 39

MLT-2

Question 40

Normal Reaction has the dimension….

Answer 40

MLT-2