Tag: measurement of distance

Questions Related to measurement of distance

Which scale is best for measuring the length of a ladybug?

  1. Millimeters

  2. Centimeters

  3. Meters

  4. Kilometers


Correct Option: B
Explanation:

The size of a ladybug is very small, of the order of centimeters. Thus centimeters is the best scale for measuring the length of a ladybug.

The least value measured with metre-scale is (if the metre scale is divided into 1000) ....................... .

  1. 1 mm

  2. 1 m 

  3. 1 cm

  4. 1 nm


Correct Option: A
Explanation:
Since, $1 \ metre$ is divided into $1000$ divisions.
Least count of metre scale  $L.C. = \dfrac{1 \ m}{1000} = 0.001 \ m = 1 \ mm$

In the above instrument while measuring an internal diameter. $ID$ is set of $321 mm$ with no zero error . if cap end is after ${17^{th}}$ division and ${17^{th}}$ division of main scale coincides with the reference line, the $ID$ is:-

  1. $321.717 mm$

  2. $321.87 mm$

  3. $328.17 mm$

  4. $324.67 mm$


Correct Option: B

The unit of the quantity $g/G$ in SI will be

  1. $kg$ ${m}^{-2}$

  2. $mk$ ${g}^{-2}$

  3. ${m}^{2}$ ${kg}^{-1}$

  4. ${kg}^{2}$ ${m}^{-1}$


Correct Option: A

Light year is the unit of following physical quantity

  1. Time

  2. Distance

  3. Mass

  4. None


Correct Option: B

The average kinetic energy $E$ of a gas molecule is given by the equation$E=\cfrac{3}{2}kT$
where $T$ is the absolute (kelvin temperature)
What are the SI base units if $k$?

  1. ${kg}^{-1}{m}^{-1}{s}^{2}K$

  2. ${kg}^{-1}{m}^{-2}{s}^{2}K$

  3. $kg$ ${ms}^{-2}{K}^{-1}$

  4. $kg{m}^{2}{s}^{-2}{K}^{-1}$


Correct Option: D
Explanation:

Here ,

$E = \dfrac{3}{2}kT$
$\implies k= \dfrac{2E}{3T}$
$\implies [k] = \dfrac{[E]}{[T]}$
$\implies [k] = \dfrac{kgm^{2}s^{-2}}{K}$
$\implies [k] = kgm^2s^{-2}K^{-1}$

What is the advantage of choosing the wavelength of light as a standard of length?

  1. Travels fast

  2. Speed independent of location and temperature

  3. No medium to travel

  4. No advantage


Correct Option: B
Explanation:

Advantage :

1) It is easy available and invariable

2) It is well defined and does not change with locations, temperature, time, pressure etc

Which of the following is not the unit of length 

  1. micron

  2. light year

  3. angstrom

  4. radian


Correct Option: D
Explanation:

Radian is not the unit of length it is the unit of angle.

The SI unit of length is the:

  1. Millimetre

  2. Centimetre

  3. Metre

  4. Kilometre


Correct Option: C
Explanation:

Metre is the SI unit of length.

Choose the correct answer from the following

  1. An area of one square centimetre is $10^4$ times greater than one square metre

  2. $1 hour\ 18 min$ is equal to $3618$ seconds.

  3. SI unit of volume is cubic metres.

  4. Metre is the standard unit to measure length


Correct Option: C,D
Explanation:

$1$ square centimeter $=(10^{-2})^2 m^2=10^{-4} m^2$

Thus, option A will be wrong.
$1 hour\ 18 min$ $=3600+(18\times 60)=3600+1080=4680 $ seconds.
So, option B will also wrong.
We know that the SI unit of volume is cubic meter and meter is the standard unit of length.
Thus, option C and D both are correct.