Tag: dynamics - explaining motion

Questions Related to dynamics - explaining motion

In the equation $\left( P+\dfrac { a }{ { V }^{ 2 } }  \right) \left( v-b \right) =RT,$ the SI unit of a is

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

  1. N ${ m }^{ 2 }$

  2. ${ m }^{ 4 }$

  3. N${ m }^{ -3 }$

  4. ${ m }^{ -2 }$

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Correct Option: C

The melting point of pure ice is

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

  1. $ 23.5^o C $

  2. $ 100^o C $

  3. 273.15 K

  4. 100 K

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Correct Option: C
Explanation:

The melting point of pure ice is $0^0C$. To convert temperature from degree Celsius to Kelvin, we add $273.15$.


So , $0^0C = (0+273)\,K = 273\,K$

Then, melting point of pure ice is $273.15\,K$.

If $10 ^ { 7 }$ erg is taken as unit of energy, $10 ^ { 5 }$ dyne as theunti of force, one second as unit of time, what is the unit of length? 

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

  1. 1$m$

  2. 10$\mathrm { m }$

  3. 100$m$

  4. none

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Correct Option: B

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

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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

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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. $10^{-6}$

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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. $10$

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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. $36 m s^{-1}$

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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

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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$^{-3}$

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Correct Option: C
Explanation:

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

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