Tag: fundamental quantities

Questions Related to fundamental quantities

Light year is a unit of:

physics measurement of physical quantities kinds of units fundamental quantities standardized measurement

  1. time

  2. distance

  3. light

  4. intensity of light

Show answer
Correct Option: B
Explanation:

Light year is a unit of $distance$.

Which one can be represented as the symbol of time?

physics measurement of physical quantities kinds of units fundamental quantities standardized measurement

  1. $m$

  2. $F$

  3. $t$

  4. None

Show answer
Correct Option: C
Explanation:

Time is generally represented by the symbol $t$.
Mass is represented by symbol $m$ and force by the symbol $F$.

The unit of electric field intensity is:

physics measurements and units kinds of units fundamental quantities standardized measurement

  1. Newton/ metre

  2. Coulomb/ newton

  3. Newton/ coulomb

  4. Joule/ newton

Show answer
Correct Option: C
Explanation:

Electric field due to a charge is given by  $E = \dfrac{F}{q}$
Unit of force is Newton $(N)$ and that of charge is Coulomb $(C)$.
So, unit of electric field is  Newton/coulomb  i.e  $N/C$

Among the following indentify the derived quantities.

physics measurement of physical quantities kinds of units fundamental quantities standardized measurement

  1. Gravitational constant

  2. Frequency

  3. Electric charge

  4. Electric current

Show answer
Correct Option: A,B,C
Explanation:

The derived quantities are gravitational constant, frequency, electric charge because they are made up of several other quantities combined to form one single quantity.

The energy which an electron acquires when accelerated, through a potential difference of $1$ volt is called

physics measurements and units kinds of units fundamental quantities standardized measurement

  1. $1$ Joule

  2. $1$ eV

  3. $1$ erg

  4. $1$ watt

Show answer
Correct Option: B
Explanation:

The energy which an electron acquires when accelerated, through a potential difference of 11 volt is called 1 eV. It is a unit of energy.  It is usually used as a measure of particle energies although it is not an SI (System International) unit. The SI unit for energy is the Joule. $1\,eV=1.602\times 10^{-19}\,Joules$

The Sl unit of length is the meter. Suppose we adopt a new unit of length which equals to $x$ meters. The area 1 $m ^ { 2 }$ expressed in terms of the new unit has a magnitude:

physics measurements and units kinds of units fundamental quantities standardized measurement

  1. $x$

  2. $x ^ { 2 }$

  3. $\dfrac { 1 } { x }$

  4. $\dfrac { 1 } { x ^ { 2 } }$

Show answer
Correct Option: D
Explanation:

SI unit of Length $=$ meters.

New Unit of Length $=x$ meters.

$1m=\dfrac 1x$ new units

SI unit of area : 

$A= 1m^2$   

$=1\times 1m^2$                        

$=\dfrac 1x\times \dfrac 1x $     

$=\dfrac{1}{x^2}$     

The impulse $J$ required to bring it to rest when it reaches the vertical position.

physics measurement of physical quantities kinds of units fundamental quantities standardized measurement

  1. Impulse of $m\sqrt {\dfrac {gl}{3}}$ when it is applied horizontally at distance $l$ from pivoted point

  2. Impulse of $m\sqrt {\dfrac {gl}{3}}$ when it is applied horizontally at distance $\dfrac {l}{2}$ from pivoted point

  3. Minimum impulse is $m\sqrt {\dfrac {gl}{2}}$ when it is applied at distance $l$ from pivoted point

  4. If rod is stopped by applying minimum impulse then the is impulse imparted by pivot is $\dfrac {m\sqrt {gl}}{2\sqrt {3}}$

Show answer
Correct Option: A

If $10 ^ { 7 }$ era is taken as unit of energy, $10 ^ { 5 }$ dyne as the unit of force, one second as unit of time. what is, the unit of length?

physics measurements and units kinds of units fundamental quantities standardized measurement

  1. $1$ $m$

  2. $10$ $m$

  3. $100$ $m$

  4. None

Show answer
Correct Option: A

The following quantities which have same directions :

physics measurements and units kinds of units fundamental quantities standardized measurement

  1. force, impulse

  2. impulse, change in momentum

  3. change in velocity, change in momentum

  4. All the above

Show answer
Correct Option: A

The MKS unit of quantity $\dfrac{\pi \eta r^4}{2}$ is :

physics measurements and units kinds of units fundamental quantities standardized measurement

  1. $N s {m}^{2} radian  $

  2. $Ns/m/Radian$

  3. $Radian/Ns/m$

  4. $ Ns/m/Radian^2 $

Show answer
Correct Option: A
Explanation:

Unit of $\pi $ is radians.

Unit of $r$ is $m$.
Unit of coefficient of viscosity, $\eta =N\, s\, { m }^{ -2 } $
Whereas $2$ is just a number, so it is unit less.
Therefore, Unit of given expression $=radian \times$ $N\, s\, { m }^{ -2 }\times { m }^{ 4 }=N\,s \, { m }^{ 2 } \ radian$