Tag: measurement of physical quantities

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Questions Related to measurement of physical quantities

Multiple choice physics measurement of physical quantities kinds of units fundamental quantities standardized measurement

The impulse $J$ required to bring it to rest when it reaches the vertical position.

  1. Impulse of $m\sqrt {\dfrac {gl}{3}}$ when it is applied horizontally at distance $l$ from pivoted point
  2. Impulse of $m\sqrt {\dfrac {gl}{3}}$ when it is applied horizontally at distance $\dfrac {l}{2}$ from pivoted point
  3. Minimum impulse is $m\sqrt {\dfrac {gl}{2}}$ when it is applied at distance $l$ from pivoted point
  4. If rod is stopped by applying minimum impulse then the is impulse imparted by pivot is $\dfrac {m\sqrt {gl}}{2\sqrt {3}}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice physics measurement of physical quantities kinds of units fundamental quantities standardized measurement

Dimensional analysis is the analysis of the relationships between different physical quantities by 

  1. identifying their fundamental dimensions

  2. units of measure

  3. tracking these dimensions as calculations or comparisons are performed.

  4. All of the above

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Dimensional analysis establishes the relation between the physical quantities by comparing the different quantities using their fundamental dimensions.

The dimensional analysis also makes use of the units to measure different quantities and the dimensional analysis is also helpful in performing several calculations.

Multiple choice physics measurement of physical quantities kinds of units fundamental quantities standardized measurement

A dimensionless quantity

  1. never has a unit

  2. always has unit

  3. may have a unit

  4. does not exit
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A dimensionless quantity is that is always independent of basic $7$ units:-meter, second, kilogram, Kelvin, Candela, ampere.

But it is not necessary. A dimensionless quantity is unitless. And eg, for this, is radian (unit of angle), which is dimensionless quantity because it is the ratio of two lengths.

Multiple choice physics measurement of physical quantities kinds of units fundamental quantities standardized measurement

Pressure (P), density $\displaystyle (\rho )$ and velocity (V) be taken as fundamental quantities for dimensional analysis.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Pressure is calculated as   $P = \dfrac{Force}{Area}$
Density  $\rho = \dfrac{Mass}{Volume}$

Velocity  $V = \dfrac{Displacement}{time}$

So, pressure, density and velocity are derived from other quantities and so, these are termed as derived quantities , not fundamental quantities.
Hence, the given statement is false.