Tag: physics

Questions Related to physics

On a hypothetical scale X, the ice point in ${ 40 }^{ \circ  }$ and then steam point is ${ 120 }^{ \circ  }$. For another scale Y the ice point and stem points are ${ -30 }^{ \circ  }$ and ${ 130 }^{ \circ  }$ respectively. If X-reads ${ 50 }^{ \circ  }$ The read of Y is 

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

  1. $-{ 5 }^{ \circ }$

  2. $-{ 8 }^{ \circ }$

  3. $-{ 10 }^{ \circ }$

  4. $-{ 12 }^{ \circ }$

Show answer
Correct Option: C

Which of the following temperature scale doesn't have negative number.

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

  1. celsius

  2. kelvin

  3. fahrenheit

  4. A.O.T

Show answer
Correct Option: B

1 dyne $=$ _____ $N$.

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

  1. $10^5$

  2. $10^{-5}$

  3. $10^6$

  4. $10^{-6}$

Show answer
Correct Option: B
Explanation:

SI unit of Force is $Newton.$
CGS unit of force is $dyne.$
$1\ N = 1\ kg m/s^{2} = 1000 g \times  100 cm/s^{2} = 100000\ dyne$

$1$ 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. $1 nm$

Show answer
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

Show answer
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.