Tag: motion and measurement

Questions Related to motion and measurement

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

The CGS unit of energy is the dye.

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:

 The CGS unit of energy is erg. The erg is a unit of energy equal to $10^{-7}$ joules.

Which quantities are measured in the same unit?

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

  1. energy, power and work

  2. energy and power, but not work

  3. energy and work, but not power

  4. power and work, but not energy

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Correct Option: C
Explanation:
Quantity             Dimension
Energy              $ML^2T^{-2}$
Work                  $ML^2T^{-2}$
Power                 $ML^2T^{-3}$

So, the dimension of energy and work is same but different to power.
Option (C) is correct.

Watt-hour measures

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

  1. current

  2. voltage

  3. power

  4. electric energy

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Correct Option: D
Explanation:

Watt is unit of power, hour is unit of time. 

Thus Watt-hour means Power x Time, which is energy.

Maxwell is the unit of

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

  1. magnetic susceptibility

  2. intensity of magnetisation

  3. magnetic flux

  4. magnetic permeability

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Correct Option: C
Explanation:

In C.G.S system, Maxwell is the unit of magnetic flux 
$1 Wb(S.I unit)=10^8\ maxwell$

Find out the odd one from the given options.

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

  1. $Calorie$

  2. $Joule$

  3. $Ampere$

  4. $Kelvin$

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Correct Option: C
Explanation:

(3) Ampere
Because Calorie,Joule and Kelvin are related to Heat.
But, Ampere is the unit of current.