Tag: units - definitions and systems

Questions Related to units - definitions and systems

Metre is the SI unit of

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

  1. mass

  2. volume

  3. length

  4. area

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Correct Option: C
Explanation:

Metre is the SI unit of length.

Pressure is a standard unit of time.

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: B
Explanation:

Second is a standard unit of time. Thus the given statement is false.

Quantity of matter contained in a body is ....................... .

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

  1. Mass

  2. density

  3. relative density

  4. Volume

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Correct Option: A
Explanation:

Mass of the body is defined as the quantity of matter contained in a body.

Knot is a measure of:

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

  1. The speed of ship

  2. The curvature of spherical objects

  3. Solar radiation

  4. Intensity of earthquake shock.

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Correct Option: A
Explanation:

Knot is a measure of the speed of ship. The term knot dates from the 17th century, when sailors measured the speed of their ship by using a device called a "common log".

Hence, option A is correct.

Which one of the following does not have unit of force per unit area:

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

  1. $Stress$

  2. $Strain$

  3. $Youngs Modulus$

  4. $pressure$

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Correct Option: B
Explanation:
  • Stress  is the force per unit area on a body that tries to cause a change in shape. It is measured by the SI unit is Pascal.

  • Strain is defined as the deformation produced in a solid due to stress. It is measured by calculating the ratio of the two lengths. As a result it does not have any unit.  

  • Force is measured by the product of mass and acceleration. Its SI unit is Newton.

  • Pressure is measured by force per unit area. Its SI unit is Pascal.

So correct answer is option (B).

The base quantity among the following is:

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

  1. Speed

  2. Weight

  3. Length

  4. Area

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Correct Option: C
Explanation:

 A base quantity is one of a conventionally chosen subset of physical quantities, where no quantity in the subset can be expressed in terms of the others. There are seven basic fundamental quantities: Length, mass, time, electric current, amount of substance, luminous intensity and temperature. So, the base quantity among the following is length.

If $L = \left( {20 \pm 0.01} \right)m$ and $B = \left( {10 \pm 0.02} \right)m$ then $\dfrac{L}{B}$ is 

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

  1. $ \left( {2 \pm 0.03} \right)m$

  2. $ \left( {2 \pm 0.015} \right)m$

  3. $ \left( {2 \pm 0.01} \right)m$

  4. $ \left( {2 \pm 0.005} \right)m$

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Correct Option: A
Explanation:

$l=20\pm 0.01, B=10\pm 0.02$

Take $l=20+0.01, B=10+0.02$
Then $\cfrac {l}{B}=\cfrac {20.01}{10.02}=1.997$
Taken $l= 20-0.01$, $B=10-0.02$
There $\cfrac {l}{B}=\cfrac {19.99}{9.98}=2.003$
$\therefore$ The answer is $(2\pm 0.003)m$ .

Gauss is the unit of -

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

  1. B

  2. H

  3. M

  4. I

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Correct Option: A
Explanation:

The Gauss (G), is the cgs unit of measurement of magnetic flux density (B). One gauss is defined as one maxwell per square centimeter.

Debye is a unit of

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

  1. rms velocity

  2. force

  3. specific gravity

  4. electric dipole moment

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Correct Option: D
Explanation:

The debye (symbol: D) is a CGS unit of electric dipole moment, named in the honour of the physicist Peter J. W. Debye.
It is defined as $ 1\times { 10 }^{ -18 }$ statcoulomb-centimetre.

Which are SI units of mass,

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

  1. Kg

  2. Gram

  3. mg

  4. ml

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Correct Option: A