Tag: fundamental and derived units

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Questions Related to fundamental and derived units

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

A physical quantity u is given by the relation $u=\dfrac{B^2}{2\mu _0}$
Here, $B=$ magnetic field strength
$\mu _o=$ magnetic permeability of vacuum
The name of physical quantity u is?

  1. Energy

  2. Energy density

  3. Pressure

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The expression B^2 / (2 * mu_0) represents the energy density of a magnetic field, which has the same units as pressure (energy per unit volume).

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

Match the columns :

I II
1. Mass a. $m/s^2$
2. Weight b. kilogram
3. Gravitational acceleration c. $Nm^2\,\,kg^{-2}$
4. Gravitational constant d. Newton 

 

  1. 1-a ,2-b ,3-c ,4-d

  2. 1-b ,2-a ,3-d ,4-c

  3. 1-b ,2-d ,3-c ,4-a

  4. 1-b ,2-d ,3-a ,4-c
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Answer is D.

The right matches are given below.

1. Mass                                   -  b. kilogramII. same everywhere
2. Weight                                -  d. Newton IV. depends on the altitude
3. Gravitational acceleration  -  a. $m/s^2$I. zero at the center
4. Gravitational constant        -  c. $Nm^2\,\,kg^{-2}$III. remain constant in the universe

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

The SI units of mass and weight are ______

  1. kg and kg

  2. N and kg

  3. kg and N

  4. N and N
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Mass is intrinsic nature of any object or material and it doesn't vary or depend on gravitational field around it.
Weight is the force experienced by an object and it depends on both the mass as well as gravitational field which it experiences in a particular place.

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

How watt is related to the fundamental units?

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

  4. Nm
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

SI unit of mass is Kg , acceleration is $ms^{-2}$ ad of velocity is $ms^{-1}$.

Now power is defined as $=$ force $\times  $ velocity, where $F=m\times a$
So, $P=m\times a\times v$ , putting the SI unit of $m, a, v$
We get SI unit of power is $kgm^2s^{-3}$.

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

Which pair of following quantities has dimensions different from each other. 

  1. Impulse and linear momentum

  2. Planck's constant and angular momentum

  3. Moment of inertia and moment to force

  4. Young's modulus and pressure
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Moment of inertia $=\dfrac { 1 }{ 2 } \times mass\times { \left( Radius\quad of\quad gyration \right)  }^{ 2 }= \left[ { M }^{ 1 }{ L }^{ 2 }{ T }^{ 0 } \right] $


Moment of force $=$ torque $= N.m = $$\left[ { M }^{ 1 }{ L }^{ 2 }{ T }^{ -2 } \right] $

Both are different from each other.