Tag: motion and measurement

Questions Related to motion and measurement

What is the  $SI$  unit of permeability?

physics motion and measurement physical quantities units - definitions and systems physical quantities like mass and weight

  1. Henry per metre

  2. Tesla metre per ampere

  3. Weber per ampere metre

  4. All the above units are correct

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Correct Option: D

The unit of ${Iq}{Z}$ is:

 $I=$Current, $Z= $Electrical Impedance and $q =$ Charge 

physics motion and measurement physical quantities units - definitions and systems physical quantities like mass and weight

  1. Newton

  2. Dyne

  3. Joule

  4. None

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Correct Option: C
Explanation:

The given relation is ${ Iq }{ Z } $, since $q=It$.


Expression is $ { { I }^{ 2 } }{ Z } t$.

This is $Electrical\quad Power\quad X\quad time$. Hence the unit is $Joule$.

If E and H represent electric field and magnetic field intensity respectively, then E/H has unit of 

physics motion and measurement physical quantities units - definitions and systems physical quantities like mass and weight

  1. Ampere

  2. Ohm

  3. Volt

  4. Joule

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Correct Option: B

Express 100 K in $^0C$

physics motion and measurement physical quantities units - definitions and systems physical quantities like mass and weight

  1. $ - {273^0}C$

  2. $ {100^0}C$

  3. $ {212^0}C$

  4. $ - {173^0}C$

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Correct Option: C

Which of the following is not a unit of heat energy?

physics motion and measurement physical quantities units - definitions and systems physical quantities like mass and weight

  1. Joule

  2. Kelvin

  3. Calorie

  4. None of these

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Correct Option: B

Which of the following is not the unit of surface tension ? 

physics motion and measurement physical quantities units - definitions and systems physical quantities like mass and weight

  1. $newton/meter$

  2. $joule/(meter)^2$

  3. $kg/(second)^2$

  4. $watt/ meter$

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Correct Option: D

The Vander waal's equation for gas is given by $\left (P + \dfrac {a}{V^{2}}\right )(V - b) = RT$ where $P$ is pressure, $V$ is volume $'a'$ and $'b'$ are constants, $R$ is universal gas constant and $T$ is absolute temperature. Then the units of $'a'$ are

physics motion and measurement physical quantities units - definitions and systems physical quantities like mass and weight

  1. $dyne\times cm^{5}$

  2. $dyne\times cm^{4}$

  3. $dyne\times cm^{3}$

  4. $dyne\times cm^{2}$

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Correct Option: B

Acceleration is defined as the rate of change of velocity. Unit of rate of change of acceleration is:

physics motion and measurement physical quantities units - definitions and systems physical quantities like mass and weight

  1. $m/s^{2}$

  2. $m/s^{3}$

  3. $m/s$

  4. $m^{2}/s^{3}$

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Correct Option: B
Explanation:

Acceleration has unit $m/{s}^{2}$.

The rate of change of acceleration $\dfrac { d\overset { \rightarrow  }{ a }  }{ dt } =\dfrac { { d }^{ 3 }y }{ d{ t }^{ 3 } } =\dfrac { m }{ { s }^{ 3 } } $
Hence, option B is correct.

To express all the physical quantities in SI units, we need 

physics motion and measurement physical quantities units - definitions and systems physical quantities like mass and weight

  1. two fundamental units

  2. three fundamental units

  3. five fundamental units

  4. seven fundamental units

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Correct Option: D
Explanation:

SI unit system contains seven fundamental quantities which are independent to each other and can be used to represent any given quantity. Hence, all physical quantities can be represented in powers of seven fundamental SI units.

Which of the following quantity is unitless ?

physics motion and measurement physical quantities units - definitions and systems physical quantities like mass and weight

  1. Velocity gradient

  2. Pressure gradient

  3. Displacement gradient

  4. Force gradient

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Correct Option: C
Explanation:

Gradient of a quantity $Q$ is given as $\dfrac{\Delta Q}{\Delta x}$
Thus, a gradient will be unitless if its numerator has same dimensions as denominator, i.e. $x$ (which has the dimension $L$).
Thus, out of the options, Displacement has the dimension $L$ and hence its gradient will be dimensionless.