M a t c h the C o l u m n I with C o l u m n I I . Column - I Column - II ( A ) Distance between earth and sun ( p ) Micron ( B ) Interatomic distance in a solid ( q ) Fermi ( C ) Size of a nucleus ( r ) Light year ( D ) Wavelength of infrared laser ( s ) Angstrom

A – r , B – s , C – q , D – p

A – p , B – q , C – r , D – s

A – q , B – p , C – s , D – r

A – s , B – r , C – p , D – q

EASY

Earn 100

Which is greater, pound or kilogram ?

Important Questions on Physical World and Measurement

EASY

Physics>Mechanics>Physical World and Measurement>Measurement of Length, Mass and Time

The nearest star to our solar system is

4.3

light years away. The distance of this star in Parsec is (Mean distance between the earth and the sun

= 1.5 \times 10^{11} m

and one light year

= 9.46 \times 10^{15} m)

HARD

Physics>Mechanics>Physical World and Measurement>Measurement of Length, Mass and Time

A person in front of a mountain is beating a drum at the rate of

40

per minute and hears no distinct echo. If the person moves

90 m

closer to the mountain, he has to beat the drum at

60

per minute to not hear any distinct echo. The speed of sound is

EASY

Physics>Mechanics>Physical World and Measurement>Measurement of Length, Mass and Time

The dimension of light year

HARD

Physics>Mechanics>Physical World and Measurement>Measurement of Length, Mass and Time

Two full turns of the circular scale of a screw gauge having

50

divisions cover a distance of

1 mm

. Further, it is found that the screw gauge has a zero error of

- 0.02 mm

. While measuring the diameter of a thin wire, a student notes the main scale reading of

4 mm

and the number of circular scale divisions in line with the main scale as

37

. The diameter of the wire is,

EASY

Physics>Mechanics>Physical World and Measurement>Measurement of Length, Mass and Time

The atomic, molecular and nuclear phenomena are the parts of ______ domain.

HARD

Physics>Mechanics>Physical World and Measurement>Measurement of Length, Mass and Time

The farthest objects in our universe discovered by modern astronomers are so distant that light emitted by them takes billions of years to reach the earth. These objects (known as quasars) have many puzzling features which have not yet been satisfactorily explained. What is the distance in km of quasar from which light takes 3.0 billion years to reach us ?

EASY

Physics>Mechanics>Physical World and Measurement>Measurement of Length, Mass and Time

The method used by astronomers to calculate how far the star is _____

HARD

Physics>Mechanics>Physical World and Measurement>Measurement of Length, Mass and Time

The thin metallic strip of vernier calipers moves downward from top to bottom in such a way that it just touches the surface of beaker. Main scale reading of caliper is

6.4 cm

whereas its vernier constant is 0.1

mm

. The

4^{th}

of vernier scale division is coinciding with main scale division. The actual depth of beaker in

mm

is (when zero of vernier coincides with zero of main scale),

EASY

Physics>Mechanics>Physical World and Measurement>Measurement of Length, Mass and Time

Size of observable universe is about

HARD

Physics>Mechanics>Physical World and Measurement>Measurement of Length, Mass and Time

It is a well known fact that during a total solar eclipse the disk of the moon almost completely covers the disk of the sun. Then the approximate diameter of the moon is:
[Assume Distance of moon from earth (

r_{M E}

) =

3.84 \times 10^{8} m

, Distance of sun from earth (

r_{S E}

) =

1.496 \times 10^{11} m

, Diameter of sun (

D

) =

1.39 \times 10^{9} m

]

MEDIUM

Physics>Mechanics>Physical World and Measurement>Measurement of Length, Mass and Time

An echo repeats two syllables. If the velocity of sound is

330 m s^{- 1}

, then the distance of the reflecting surface is

EASY

Physics>Mechanics>Physical World and Measurement>Measurement of Length, Mass and Time

How many wavelengths of

K r^{86}

are there in one metre?

HARD

Physics>Mechanics>Physical World and Measurement>Measurement of Length, Mass and Time

The principle of 'parallax' is used in the determination of distance of very distant stars. The baseline AB is the line joining the earth's two locations six months apart in its orbit around the sun. That is, the baseline is about the diameter of the earth's orbit = 3 × 10¹¹ m. However, even the nearest stars are so distant that with such a long baseline, they show parallax only of the order of 1'' (second) of are or so A parsec is a convenient unit of length on the astronomical scale. It is the distance of an object that will show a parallax of 1" (second) of arc from opposite ends of a baseline equal to the distance from the earth to the sun. How much is a parsec in terms of meters ?

EASY

Physics>Mechanics>Physical World and Measurement>Measurement of Length, Mass and Time

Light year is a unit for the measurement of

MEDIUM

Physics>Mechanics>Physical World and Measurement>Measurement of Length, Mass and Time

Compressional wave pulse are sent to the bottom of sea from a ship and the echo is heard after

2 s

. If bulk modulus of elasticity of water is I

2 \times 10^{9} N m^{- 2}

and mean temperature is

4 ° C

, the depth of the sea will be

MEDIUM

Physics>Mechanics>Physical World and Measurement>Measurement of Length, Mass and Time

Sound waves of $ν = 600 Hz$ fall normally on a perfectly reflecting wall. The shortest distance from the wall at which all particles will have maximum amplitude of vibration will be (speed of sound $= 300 m s^{- 1}$ )

MEDIUM

Physics>Mechanics>Physical World and Measurement>Measurement of Length, Mass and Time

If man is standing unsymmetrical (not equidistance from both the cliffs) between parallel cliffs, claps his hands and starts hearing a series of echoes at a intervals of

1 s

. If speed of sound in air is

340 m s^{- 1}

, the distance between two cliffs would be

EASY

Physics>Mechanics>Physical World and Measurement>Measurement of Length, Mass and Time

M a t c h

the

C o l u m n I

with

C o l u m n I I

	Column - I		Column - II
$(A)$	Distance between earth and sun	$(p)$	Micron
$(B)$	Interatomic distance in a solid	$(q)$	Fermi
$(C)$	Size of a nucleus	$(r)$	Light year
$(D)$	Wavelength of infrared laser	$(s)$	Angstrom

HARD

Physics>Mechanics>Physical World and Measurement>Measurement of Length, Mass and Time

A laser is a source of very intense, monochromatic and unidirectional beam of light. These properties of a laser light can be exploited to measure long distances. The distance of moon from the earth has been already determined very precisely using a laser as a source of light. A laser light beamed at the moon takes

2.56 s

to return after reflection at the moon's surface. How much is the radius of lunar orbit around the earth ?

EASY

Physics>Mechanics>Physical World and Measurement>Measurement of Length, Mass and Time

The recording of the readings needs lot of _____ and the least count of the objects used should be the minimum. (precision/effort)

Which is greater, pound or kilogram ?

Important Questions on Physical World and Measurement

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