Tag: measurements and units

Questions Related to measurements and units

Name the physical quantities related to joule.

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

  1. mass

  2. energy

  3. pressure

  4. intensity

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Correct Option: B
Explanation:
Energy is measured in joule.

Write the derived unit of pressure.

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

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

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

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

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

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Correct Option: A
Explanation:
$Pressure=\dfrac{Force}{Area}=\dfrac{Mass \times Acceleration}{Area}$
$Pressure=kg\times ms^{-2}/m^2=kgm^{-1}s^{-2}$

Name the physical quantities which are measured in the $ns$.

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

  1. Time

  2. Mass

  3. Length

  4. Temperature

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Correct Option: A
Explanation:
$1\ ns=10^{-9}\ seconds$
So the physical quantity measured in $ns$ is time.

$Js$ is the unit of

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

  1. Energy

  2. Angular Momentum

  3. Momentum

  4. Power

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Correct Option: B
Explanation:

$Js$ $\rightarrow  M^{1} L^{2} T^{-1}$
Energy $= M^{1} L^{2} T^{-2}$
Angular Momentum $= mvr = M^{1} L^{2} T^{-1}$
Momentum $= mv = M^{1} L^{1} T^{-1}$
Power $= f\times v = M^{1} L^{2} T^{-3}$
Hence, option B is correct.

The SI unit of magnetic permeability is:

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

  1. ${ Am }^{ -1 }$

  2. ${ Am }^{ -2 }$

  3. ${ Hm }^{ -2 }$

  4. ${ Hm }^{ -1 }$

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Correct Option: D
Explanation:
Magnetic permeability is a constant of proportionality that exists between magnetic induction and magnetic field intensity. 

In SI units, permeability is measured in henries per meter $H/m$ or $H m^{-1}$.

Which is not the unit of Force:

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

  1. Poundal

  2. Dyne

  3. Joule

  4. Newton

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Correct Option: C
Explanation:

Joule is not the unit of force, it is the SI unit of work.

Which of the following is different from others ?

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

  1. Mass

  2. Length

  3. Time

  4. Density

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Correct Option: D
Explanation:

Mass, length and time are the fundamental physical quantities whereas density is the derived physical quantity.

Density is a ________ physical quantity.

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

  1. fundamental

  2. derived

  3. semi-derived

  4. semi-fundamental

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Correct Option: B
Explanation:
Density is calculated from mass and volume by the relation   $\rho = \dfrac{m}{V}$
Since, density depends on other fundamental quantity for its measurement.
So, density is a derived physical quantity.

The effect of an impulse force on the body is measured only in terms of its

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

  1. Force

  2. Moment of momentum

  3. Impulse

  4. None of these

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Correct Option: C
Explanation:

The effect of an impulse force on the body is measured only in terms of impulse. If a moving object is stopped by an impact, the change in momentum of the object occurs. This change in momentum is called the impulse.

Energy cannot be measured in

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

  1. $Js$

  2. $Ws$

  3. $kWh$

  4. $erg$

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Correct Option: A
Explanation:

$W \ s$, $kWh$ and $erg$ are the unit of energy but $J \ s$ is not the unit of energy. So, energy cannot be measured in $J \ s$