Tag: system of unit

Questions Related to system of unit

$1$ Newton$=$ $K$ dyne, then what is the value of $K$?

physics dynamics - explaining motion system of unit summary of si units system of units

  1. $1$

  2. $10^2$

  3. $10^5$

  4. $10$

Show answer
Correct Option: C
Explanation:

Newton is in SI units that is Kg metre per second whereas Dyne is in Gram centimetre per second.

We know that $1 Kg = 1000 gm$ where as $1 metre = 100 cm$.
Hence to convert from SI units to CGS unit, we will have to multiply by a factor that is $1000\times100$.
$K=10^{5}$

Express the speed $36 km h^{-1}$ in $m s^{-1}$.

physics dynamics - explaining motion system of unit summary of si units system of units

  1. $3600 m s^{-1}$

  2. $10 m s^{-1}$

  3. $0.6 m s^{-1}$

  4. $36 m s^{-1}$

Show answer
Correct Option: B
Explanation:

$36\ km h^{-1}=\dfrac{36 km}{1h}=\dfrac{36 \times 1000 m}{60 \times 60 s}$$=10 m s^{-1}$

$\displaystyle kg{ ms }^{ -1 }$ is the SI unit of

physics dynamics - explaining motion system of unit summary of si units system of units

  1. Impulse

  2. Force

  3. Angular velocity

  4. None of these

Show answer
Correct Option: A
Explanation:

Impulse $(I)$ imparted to the body is equal to the change in linear momentum $(\Delta p)$ of the body.


Impulse, $I=\Delta p$

Thus momentum has the same units as that of impulse. Since momentum has S.I. unit as $kgms^{-1}$, impulse also has S.I. unit as $kgms^{-1}$.

Density of mercury in MKS is 13600 kg m$^{-3}$ then in CGS is:

physics dynamics - explaining motion system of unit summary of si units system of units

  1. 1.36 g m$^{-3}$

  2. 13.6 kg cm$^{-3}$

  3. 13.6 g cm$^{-3}$

  4. 1.36 kg m$^{-3}$

Show answer
Correct Option: C
Explanation:

CGS unit of density is $g cm^{-3}$

Thus, $13600 kg /m^{3}=13600\times \dfrac{10^{-3}g}{10^6 cm^3}=13.6 g$ $cm^{-3}$

If 1 g cm$^{-3} = 10^3\,kg\, m^{-3}$ then $10^6kgm^{-3}=$

physics dynamics - explaining motion system of unit summary of si units system of units

  1. $10^{-3}\,g\,cm^{-3}$

  2. $10^{6}\,g\,cm^{-3}$

  3. $10^{3}\,g\,cm^{-3}$

  4. $10^{-6}\,g\,cm^{-3}$

Show answer
Correct Option: C
Explanation:

Given, $1 g cm^{-3}=10^3 kgm^{-3}$

If we multiply $10^3$ on both sides, $10^3 g cm^{-3}=10^3\times 10^3 kgm^{-3}$
or $10^3 g cm^{-3}=10^6 kgm^{-3}$
Thus, option C will be the right option. 

$1^o A$ is ____

physics dynamics - explaining motion system of unit summary of si units system of units

  1. $10 nm$

  2. $0.1 nm$

  3. $100 nm$

  4. $1 nm$

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Correct Option: B
Explanation:

$1 ^oA=10^{-10} m=10^{-1}\times 10^{-9} m=0.1 nm$   (as $1 nm=10^{-9}m$)

Which among the following is the smallest prefix?

physics dynamics - explaining motion system of unit summary of si units system of units

  1. milli

  2. nano

  3. fermi

  4. deci

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Correct Option: C
Explanation:

Here, $1$ milimeter $=10^{-3}$ meter ;

$1$ angstrom $=10^{-10}$ meter ;
$1$ fermi $=10^{-15}$ meter, 

Therefore, the smallest prefix is for fermi.

Temperature can be expressed as a derived quantity in terms of :

physics dynamics - explaining motion system of unit summary of si units system of 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 cannot be expressed in the terms of mass, length and time. Temperature is expressed in kelvin.

The physical quantity having the same unit in all the systems of unit is :

physics dynamics - explaining motion system of unit summary of si units system of units

  1. length

  2. mass

  3. time

  4. foot

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Correct Option: C
Explanation:

Time has same unit, second, in the SI, FPS, CGS and  MKS system. Rest of the quantities have different units in  SI, FPS, CGS and MKS system.

A ______ is the interval from one noon to the next noon.

physics dynamics - explaining motion system of unit summary of si units system of units

  1. mean solar day

  2. solar day

  3. lunar day

  4. day

Show answer
Correct Option: B
Explanation:

A solar day is the interval from one noon to the next noon.