Tag: physics

Questions Related to physics

Three of these quantities have the same unit. Which quantity has a different unit ?

physics measurements and units some examples of derived units fundamental and derived quantities fundamental and derived units

  1. $\dfrac{distance}{energy}$

  2. $force$

  3. $power\times time$

  4. rate   of change of momentum

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Correct Option: A

Pascal is a unit of 

physics measurements and units some examples of derived units fundamental and derived quantities fundamental and derived units

  1. Pressure

  2. Force

  3. Linear momentum

  4. Energy

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Correct Option: A
Explanation:

The pascal $(Pa)$ is the SI derived unit of pressure used to quantify internal pressure, stress, Young's modulus and ultimate tensile strength. The unit, named after Blaise Pascal, is defined as one newton per square metre.

The unit of $\dfrac{d^{2}y}{dx^{2}}$ is [where y is energy and x is distance]

physics measurements and units some examples of derived units fundamental and derived quantities fundamental and derived units

  1. $\dfrac{J^{2}}{m^{2}}$

  2. $\dfrac{J^{2}}{m}$

  3. $\dfrac{J}{m}$

  4. $\dfrac{J}{m^{2}}$

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Correct Option: D

Curie is the unit of 

physics measurements and units some examples of derived units fundamental and derived quantities fundamental and derived units

  1. decay constant

  2. radio-activity

  3. half-life

  4. average life

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Correct Option: B
Explanation:

We measure the intensity of radioactive emission by  number of atoms that get transformed to new atoms per unit time. 
Curie(Ci) is the standard unit used for measuring radio-activity.
Curie is defined as the emission rate of 1g of radium which is equal to $3.7 \times 10^{10}$ transformations per second.

The magnetic moment of electron is :

physics measurements and units some examples of derived units fundamental and derived quantities fundamental and derived units

  1. $ 9.27\times 10^{-24} $ Joule/Tesla

  2. $ 9.27\times 10^{-24} $ Tesla/Joule

  3. $ 9.27\times 10^{-23} $ Joule/Tesla

  4. $ 9.27\times 10^{-23} $ Tesla/Joule

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Correct Option: A
Explanation:

Electrons spinning on their axes are magnetic dipoles that may or may not cancel out each other depending on the type of dipole.
We measure the  magnetic moment of electron in Joule / Tesla.
The value of magnetic dipole of an electron is $9.27 \times 10^{-24}$ Joule/Tesla.   

The kilowatt hour is a unit of energy.

physics measurements and units some examples of derived units fundamental and derived quantities fundamental and derived units

  1. True

  2. False

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Correct Option: A
Explanation:

The kilowatt-hour ( kWh) is a unit of energy equal to 3600 kilojoules. The kilowatt-hour is a composite unit of energy equal to one kilowatt (kW) of power sustained for one hour.

Unit of gravitational potential energy is ______.

physics measurements and units some examples of derived units fundamental and derived quantities fundamental and derived units

  1. $J/s$

  2. $Js$

  3. $Nm$

  4. $N/m$

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Correct Option: C
Explanation:

Gravitational Potential Energy, $U=mgh$


    $ =kg\times ms^{-2}\times m$


     $= Nm$    $ (kgms^{-2} =N)$

The $SI$ unit of specific heat capacity is $J\ kg^{-1}K^{-1}$.
What is the unit of specific heat capacity expressed in $SI$ base units?

physics measurements and units some examples of derived units fundamental and derived quantities fundamental and derived units

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

  2. $kgms^{-2}K^{-1}$

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

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

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Correct Option: C
Explanation:
we know that J is the unit of work done 
So,
$J = kgm^2s^{-2} $
$\implies Jkg^{-1}K^{-1}= kgm^2s^{-2} \times kg^{-1}K^{-1}$
$\implies Jkg{-1}K^{-1}= m^2s^{-2}K^{-1}$
 
So, option C is correct answer.

Which of the following is a derived physical quantity?

physics measurements and units some examples of derived units fundamental and derived quantities fundamental and derived units

  1. Mass

  2. Velocity

  3. Length

  4. Time

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Correct Option: B
Explanation:

Mass, Length & Time are fundamental physical quantity while velocity is derived physical quantity.

Temperature can be expressed as derived quantity in terms of the following

physics measurements and units some examples of derived units fundamental and derived quantities fundamental and derived units

  1. Length and mass

  2. Mass and time

  3. Length, mass and time

  4. None of these

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Correct Option: D
Explanation:

Temperature is one of the basic (fundamental) physical quantities.