Tag: summary of si units

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

If unit of mass, length and time are tripled, then unit of energy becomes:

  1. $3$

  2. $\dfrac{1}{3}$

  3. $9$

  4. $\dfrac{1}{9}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Unit of Energy $kg\,m^2/s^2$

Unit of length $= m$ (metre)

Unit of mass $= kg$ (kilogram)

Unit of time $= s$ (second)


Thus unit of energy in terms of unit of mass, length and time is given by,

$Unit \,of\, Energy =\dfrac{(Unit\,of\,mass)\times(Unit\,of\,length)^2}{(Unit\,of\,time)^2}$

If the unit of mass, length and time are tripled the unit of energy will be,

$Unit \,of\, Energy =\dfrac{(3\times Unit\,of\,mass)\times(3\times Unit\,of\,length)^2}{(3\times Unit\,of\,time)^2}$

$Unit \,of\, Energy =3\times \dfrac{(Unit\,of\,mass)\times(Unit\,of\,length)^2}{(Unit\,of\,time)^2}$

$Unit\,of\,energy=3\times Unit\,of\,energy$

Therefore, if the unit of mass, length and time are tripled, the unit of energy will be, 3 times more than the original unit of energy.
Multiple choice physics dynamics - explaining motion system of unit summary of si units system of units

If a thermometer reads freezing point of water at 20 degree Celsius and boiling point as 150 degree Celsius, how much thermometer can read when the actual temperature is 60 degree Celsius?

  1. 98 degrees celsius

  2. 10 degree Celsius

  3. 40 degree Celsius

  4. 60 degree Celsius
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Using linear interpolation: (T - 20) / (150 - 20) = (60 - 0) / (100 - 0). (T - 20) / 130 = 60 / 100 = 0.6. T - 20 = 78, so T = 98.

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

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 

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

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

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

  4. $-{ 12 }^{ \circ }$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Scale X: (50 - 40) / (120 - 40) = 10 / 80 = 1/8. Scale Y: (T_y - (-30)) / (130 - (-30)) = (T_y + 30) / 160. Setting them equal: 1/8 = (T_y + 30) / 160. 20 = T_y + 30. T_y = -10.

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

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

  1. $1$

  2. $10^2$

  3. $10^5$

  4. $10$
Reveal answer Fill a bubble to check yourself
C Correct answer
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 $1000\times100$.
$K=10^{5}$