Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

physics > Units > Flashcards

Units Flashcards

You may prefer our related Brainscape-certified flashcards:
Physics 101 flashcards AP® Physics flashcards
1
Q

For a quantity to be a physical quantity:

A

It should be measurable.
It should explain physical happenings
It should express physical happenings in form of laws.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Why are emotions not a physical quantity

A

It is not measurable.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Physical quantity is represented by

A

Q

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

In a physical qty the relationship between its magnitude and unit.

A

Magnitude is inversely proportional to the unit.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

3 types of physical quantities

A

Ratio (magnitude only)
Scalar (magnitude and unit)
Vector (magnitude,unit and direction)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Physical quantity in form of ratio of 2 similar quantities have no

A

Units.
E.g. Relative density =
Density of object/Density of water (4°C)

(Exception : Angle)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

E.g. of physical quantities in form of ratio of 2 similar quantities

A

Relative density
Refractive index
Angle.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Mass of the electron and the sun

A

Electron : 9.1 x 10 raised to -31

Sun : 2 x 10 raised to 30 (ntomo)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

1 mile = ……… km

A

1.6 (d - j)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Fermi short form

A

fm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Chandra Shekhar unit short form

A

CSU

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Astronomical unit short form

A

A.U

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

X-ray unit short form

A

XU

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

1 X-ray unit =

A

10 raised to -13 m.

do : dm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

1 light yr

A

9.46 x 10 raised to 15 m.

b-rj , to:tL
Bridge total.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Parsec short form

A

pc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

1 CSU :

A

1.4 times the mass of sun = 2.8 x 10³⁰

n-v, do:mo
Envy domo

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

1 pc =

A

3.26 light yrs.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

1 metric tonne =

A

1000 kg.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

1 quintal =

A

100 kg.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

1 amu =

A

1.67 x 10⁻²⁷

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Work dimensional formula

A

ML²T⁻²

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

C.G.S unit of work

A

erg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

1 joule = ……… ergs

A

1 crore ergs.

10 million ergs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Many physical quantities have the same …..

A

Dimensions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

We round off measurements on the basis rules established by

A

Convention.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Absolute error in the measurement of a physical quantity is

A

The difference between the true value and the measured value.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Fundamental physical quantities also called as

A

Absolute quantities or Base quantities.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

3 properties of fundamental quantities

A

Independent of all other quantities
Do not require help of any other physical qty for their definition
Expresses other quantities.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

CGS system of units is also called as

A

Gaussian system of units.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

In the earlier systems of units, the fundamental qtys were only :

A

Length, mass and time.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

MKS system is also called as

A

Giorgi system.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

In FPS system, the unit of force is

A

Poundal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

1 lunar month = …… days

A

27.3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Lunar month definition

A

Time taken by the moon to complete 1 revolution around the Earth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

1 Shake =

A

10⁻⁸ seconds.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

SI system is also known as

A

International system of units

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

No of fundamental qtys in SI system

A

7

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

7 Fundamental qtys in SI system

A

M E T(2) A L(2)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Luminous intensity is measured in

A

Candela (cd)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

1 kg = ………… atoms

A

5.0188 x 10²⁵ atoms of carbon 12.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

1 kg is taken as the mass of a ….

A

Cylinder made of platinum-iridium alloy kept at International Bureau of Weights and Measures at Sevres near Paris,France.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Symbol of impulse

A

I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Pressure and Power is represented commonly by the same symbol

A

P

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Linear momentum is represented by

A

p

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

Kinetic energy symbol and unit

A

Unit : joules

Symbol: KE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q
  1. 251 is rounded as
  2. 25 is rounded as
  3. 35 is rounded as
A
  1. 3 (5 is followed by numbers greater than 0)
  2. 2 (the preceding digit is even : 2)
  3. 4 (preceding digit is odd : 3)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

Unit and symbol of electric charge

A

Unit : Coulomb

Symbol : q

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

Electric current unit and symbol

A

Unit : Ampere

Symbol : I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

Power SI unit and symbol

A

Unit : Watt

Symbol : P

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

Pressure unit

A

Pascal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

Electric potential unit and symbol

A

Symbol : V

Unit : Joules/Coulomb

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

ML²T⁻² is the dimensional formula of

A

Work,energy,torque.

54
Q

Significant figures definition

A

Significant figures in the measured value of a physical qty tell the number of digits in which we have confidence.

55
Q

Larger the number of significant figures obtained in a measurement greater is the

A

Accuracy

56
Q

Rules observed in counting the number of significant figures

A

All non zero digits are significant
A zero becomes significant only if it is between 2 no zero digits or if situated in the right side of the number.
In exponential notation, the numerical portion gives the number of significant figures.

57
Q

No of significant figures in

1.32 x 10⁻²

A

3 (only take the numerical portion)

58
Q

Absolute error in the measurement of a physical qty is the

A

Magnitude of difference between the true value and the measured value.

59
Q

Absolute error can be both

A

Positive and negative.

60
Q

If the true value of a physical quantity is unknown then how would we calculate it

A

1) we measure the physical quantities n times.
2) take the arithmetic mean of all these measurements.
3) this mean value is taken as the true value of the physical qty.

61
Q

Mean absolute error is represented by

A

___

∆a

62
Q

Mean absolute error is the

A

Arithmetic mean of all the magnitudes of absolute errors.

63
Q

Relative density =

A

Density of object/Density of water at 4°C

64
Q

Refractive index =

A

Velocity of light in air / velocity of light in medium.

65
Q

Exceptional physical qty in the form of ratio

A

Angle = arc/radius

Even though it has only a numerical value a unit such as degrees or radians is also used.

66
Q

Physical qtys that are neither scalar nor vector are called

A

Tensors

67
Q

System of units definition

A

It is a COMPLETE SET of units ; including both fundamental and derived units ; used for representing all kinds of physical quantities.

68
Q

1 metre is defined as the the distance travelled by light in a time interval of

A

1/299,792,458 part of a second.

np pk pn RLV

69
Q

Exa,peta,tera,giga,mega are represented by

A

E,P,T,G,M

70
Q

pico,femto,atto are represented by

A

p,f,a

71
Q

Name SI prefixes

A

Exa,peta,tera,giga,pico,femto,atto etc.

72
Q

Derived quantities are expressed as a

A

Product of differ powers of the fundamental qtys.

73
Q

Spring constant unit and symbol.

A

Symbol : k

Unit : Newton/metre

74
Q

Gravitational constant unit and symbol.

A

Symbol : G

Unit : N m²/ kg²

75
Q

Intensity of gravitational field unit and symbol

A

Symbol : E[g]

Unit : N/kg

76
Q

Gravitational potential unit and symbol

A

Unit : V[g]

Symbol : Joules/kg

77
Q

Surface tension unit and symbols

A

Symbol : T

Unit : N/m or Joules/m²

78
Q

Temperature symbol and unit

A

Symbol : T

Unit : Kelvin

79
Q

Heat symbol and unit

A

Symbol : Q

Unit : Joules

80
Q

Specific heat symbol and unit

A

Symbol : c

Unit : Joules/kg-K

81
Q

Thermal capacity symbol and unit

A

Symbol : C

Unit : Joules/K

82
Q

Latent heat symbol and unit

A

Symbol : L

Unit : Joules/kg

83
Q

Dimensions of a physical qty

A

Powers to which fundamental quantities must be raised in order to express the given physical quantity.

84
Q

Dimensional equation e.g.

A

[force] = [MLT⁻²]

85
Q

In a dimensional equation such as

[force] = [MLT⁻²] ; the square brackets are used to indicate that

A

The equation is among the dimensions and not among the magnitudes.

86
Q

Dimensional formula vs dimensional equation

A

Dimensional formula:
[force] = [MLT⁻²]

Dimensional equation
(RHS of the formula):

[MLT⁻²]

87
Q

Derived qtys

A

All other physical quantities that can be derived by suitable multiplication or division of different powers of the fundamental quantities.

88
Q

The supplementary units are

A

Radians (rad) for plane angle

Steradian (sr) for solid angle

89
Q

1 metre is defined as

A

The distance containing certain no of wavelengths of light.

Here the light is :
Orange red light emitted by an atom of krypton-86.

The no of wavelengths:
1650763.73
(d - gl - ok - gn - kn)

90
Q

Density symbol an unit

A

Symbol : d

Unit : kg/m*3

91
Q

Angular displacement unit and symbol

A

Symbol : θ

Unit : Radians (rad)

92
Q

Angular velocity symbol and unit

A

Symbol : ω (omega)

Unit : Radians/sec

93
Q

Angular acceleration symbol and unit

A

Symbol : α

Unit : Radians/sec*2

94
Q

Permittivity of free space symbol and unit

A

Symbol : ε₀

Unit : (Coulomb)2 / Newton-meter2

95
Q

Resistance symbol and unit

A

Symbol : R

Unit : Volt/Ampere or ohm

96
Q

Resistivity symbol and unit

A

Symbol : ρ (rho)

Unit : ohm-meter.

97
Q

The principle used to check dimensional correction of a given physical relation :

A

Principal of homogeneity.

98
Q

Principal homogeneity :

A

According to this principle, the dimensions of EACH TERM in a physical relation should be same.
E.g.

X = A ± (BC)² ± √(DEF)

[X] = [A] = [(BC)²] = [√(DEF)]

99
Q

Even though the a physical relation is dimensionally correct it does not mean that it is always

A

Physically correct.

100
Q

Measuring process is essentially a process of

A

Comparison.

101
Q

The FINAL RESULT OF MEASUREMENT is written as

A

___
a = true value ± ∆a
___
∆a : mean absolute error.

Here the true value is actually the mean value of all the observations.

102
Q

The fundamental quantities in mechanics are

A

Length , mass and time

103
Q

The fundamental quantities of mechanics (length,mass and time) are arbitrarily chosen ?

A

In fact any three quantities in mechanics can be termed as fundamental quantities.
E.g.
If speed and time are fundamental qtys, then length would become a derived quantity (speed x time).

104
Q

Mole :

A

Amount of substance that contains as many elementary entities as the no of atoms in .012 kg of Carbon 12.

105
Q

Moment of inertia symbol and unit

A

Symbol : I(i)

Unit : kg-mg*2

106
Q

Torque symbol and unit

A

Symbol : τ (tau)

Unit : Newton-metre

107
Q

Angular momentum symbol and unit

A

Symbol : L

Unit : Joule-sec

108
Q

Conductance symbol and unit

A

Symbol : G or 1/R

Unit : ohm⁻¹

109
Q

Conductivity symbol and unit

A

Symbol : σ, 1/ρ

Unit : ohm⁻¹ meter⁻¹

110
Q

Intensity of electric field symbol and unit

A

Symbol : E

Unit : volt/metre ; Newton/Coulomb

111
Q

Fundamental units ?

A

Any unit used for a fundamental qty.

E.g. light yr

112
Q

Gas constant symbol and unit

A

Symbol : R

Unit : Joule / kg-K

113
Q

Boltzmann constant symbol and unit

A

Symbol : k

Unit : Joule/K

114
Q

Coefficient of thermal conductivity symbol and unit

A

Symbol : K

Unit : Joule /m-s-K

115
Q

Stefan’s constant symbol and unit

A

Symbol - σ

Unit - joule/m²-K⁴

116
Q

Wien’s constant symbol and unit

A

Symbol : b

Unit : Watt-meter

117
Q

Permeability of free space symbol and unit

A

Symbol : μ

Unit : Newton/ampere*2

118
Q

In addition or subtraction of observations of various measurements, the no of decimal places taken for the resultant is

A

The number of least decimal places found in the observations.

119
Q

In multiplication or division of observations of various measurements, the no of significant figures taken for the resultant is

A

The number of least significant figures found in the observations.

120
Q

The absolute is the magnitude of difference between the

A

True value (mean value) and measured value.

121
Q

Relative error is also known as

A

Fractional error

122
Q

Relative error is defined as the

A

Ratio of the mean absolute error to the mean value.

123
Q

Percentage error is just the

A

Fractional error represented in %

124
Q

Sidereal vs Solar day

A

An Earth day can be measured in different ways.

Measure the time it takes for a complete rotation of Earth around its axis.
Measure the time it takes for the Sun to appear in the same meridian in the sky. This interval is known as the solar day.
Measure the time it takes for a distant star to appear in the same meridian in the sky. This interval is known as the sidereal day. The time interval mentioned in (1) is equal to the sidereal day. Why?
Because these stars aware very distant.

1 complete rotation of Earth around its axis takes 23 hours, 56 minutes and 4.1 seconds

Sidereal day is also 23 hours, 56 minutes and 4.1 seconds by definition.

Solar day is longer than the sidereal day

Earth moves a little less than a degree around the Sun during the time it takes for 1 full axial rotation. So, for the Sun to appear on the same meridian in the sky again after 1 full axial rotation, the Earth has to rotate one extra degree to bring the Sun into the same apparent meridian in the sky. This is why the solar day is longer than the sidereal day by about 4 minutes.

125
Q

Sidereal day is shorter than solar day by

A

Approx. 4 min

126
Q

1 solar year = ……….. avg solar days

A

365.25

127
Q

1 solar yr = ………. sidereal days

A

366.25

128
Q

Why does the duration of solar days vary

A

Earth’s orbit is an ellipse so the Earth moves faster on its orbit around the Sun when it is nearest the Sun (perihelion) and slower when it is farthest from the Sun (aphelion). This causes the duration of solar days to change.

129
Q

Coefficient of self induction symbol and units

A

Symbol : L

Unit : Volt-second/Ampere

130
Q

Magnetic flux unit

A

Units : Volt-second
Weber
Henry

131
Q

Code for symbols of mechanical qtys

A

A4 VAD PIG

KE,F2,Eta

physics (17 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions