Tag: units - definitions and systems

Questions Related to units - definitions and systems

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

physics motion and measurement physical quantities units - definitions and systems physical quantities like mass and weight

  1. Impulse

  2. Force

  3. Angular velocity

  4. None of these

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Correct Option: A
Explanation:

Impulse is defined as the change in momentum and thus impulse has the unit of momentum i.e.  $kg \ m/s$

Velocity gradient is defined as "change in velocity per unit distance". Then its unit in F.P.S. system is ____ .

physics motion and measurement physical quantities units - definitions and systems physical quantities like mass and weight

  1. $\displaystyle foot \ { s }^{ -1 }$

  2. $\displaystyle { s }^{ -1 }$

  3. $foot \ s$

  4. $pound \ s$

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Correct Option: B
Explanation:

The velocity gradient is defined as the change in velocity per unit distance.

$Velocity\ gradient=\dfrac{\Delta v}{\Delta x}$

Using the respective dimensions of $v$ and $x$.
$Velocity\ gradient=\dfrac{[LT^{-1}]}{[L]}$

So, its unit will be $sec^{-1}$.

Light travels at maximum speed in-

physics motion and measurement physical quantities units - definitions and systems physical quantities like mass and weight

  1. Air

  2. Water

  3. Vacuum

  4. None of these

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Correct Option: C
Explanation:

Light travels at approximately 300,000 kilometers per second in a vacuum, which has a refractive index of 1.0, but it slows down to 225,000 kilometers per second in water (refractive index = 1.3) and 200,000 kilometers per second in glass (refractive index of 1.5). The interaction of the light with the particles in the medius causes the delay.

Kilogram, gram, newton
 The odd one among the above stated quantities is :-
physics motion and measurement physical quantities units - definitions and systems physical quantities like mass and weight

  1. newton

  2. Kilogram

  3. gram

  4. None

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Correct Option: A
Explanation:

Gram and kilogram are the units of mass whereas newton is the unit of weight (force).

What is the full form of S.I. in S.I. system?

physics motion and measurement physical quantities units - definitions and systems physical quantities like mass and weight

  1. Standard initiative

  2. Sponsored initiative

  3. Standard international

  4. Sponsored international

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Correct Option: C
Explanation:

S.I system (standard international system). 

In this system the units of mass, length and time are same, as that of M.K.S system. 
However, it is an enlarged system encompassing all fundamental units.

Standard of unit is reproducible.

physics motion and measurement physical quantities units - definitions and systems physical quantities like mass and weight

  1. True

  2. False

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Correct Option: A
Explanation:

One of the properties of the units is standard unit should be reproducible. It means that the standard unit can be used repetitively to retain consistency of units, independent of space and time.

Hence, the given statement is true.

The unit of magnetic field is?

physics motion and measurement physical quantities units - definitions and systems physical quantities like mass and weight

  1. Weber/m

  2. Weber$/m^2$

  3. Weber

  4. Weber $\times$ meter

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Correct Option: B
Explanation:

SI unit of magnetic field is  $Weber/m^2$. Other units of magnetic field are $Tesla$ and $Gauss$.
Also,  $1 \ Tesla = 10^4 \ Gauss$

SI Unit of intensity of light is: 

physics motion and measurement physical quantities units - definitions and systems physical quantities like mass and weight

  1. Newton

  2. Kelvin

  3. Kilogram

  4. Candela

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Correct Option: D
Explanation:

Candela is the SI unit of intensity of light.

Which of the Quantity consists of unit as kg-m/sec ?

physics motion and measurement physical quantities units - definitions and systems physical quantities like mass and weight

  1. Speed

  2. Momentum

  3. Acceleration

  4. Impulse

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Correct Option: B,D
Explanation:

1.  For Speed :

    $v = \dfrac{distance}{time} = m/sec$

2. For Momentum : 
   $P = m \times v$

   Units :  $kg - m/ sec$

3. For Acceleration :
    $a = \dfrac{\Delta v}{\Delta t}=m/{sec}^2$

4. For Impulse :
    $I =F\times \Delta t = \Delta p$
     Units : $N-sec  = (kg-m/{sec}^2) \times sec = kg-m/sec$

From above we can say that $Momentum$ and $Impulse$ have same unit as kg-m/sec.
      

What is the approximate diameter of human hair?

physics motion and measurement physical quantities units - definitions and systems physical quantities like mass and weight

  1. $500$nm

  2. $5000$nm

  3. $50$nm

  4. $50000$nm

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Correct Option: D
Explanation:

Diameter of human hair is $50000$nm.