Tag: measurements and units

Quizzes (10) Questions (257)

Questions Related to measurements and units

Multiple choice physics measurements and units summary of si units fundamental quantities system of units

Find the unit of the following derived quantities: 
(a) Force [Hint: Force = Mass $\times$ acceleration]
(b) Pressure $\left[Hint: Pressure =\frac{force}{Area}\right]$

  1. $kg\,m\,s^{-2}$ and $kg\,m^{-1}\,s^{-2}$
  2. $kg\,m\,s^{-1}$ and $Kg\,m^{-2}\,s^{-1}$
  3. $ N$ and $ Pa$

  4. None of these
Reveal answer Fill a bubble to check yourself
A,C Correct answer
Explanation
Force   $F = ma$
So, unit of force is  $kg \ m/s^2$
Newton $(N)$ is also the unit of force.
Pressure   $P = \dfrac{F}{A}$
Unit of pressure   $ = \dfrac{kg \ m/s^2}{m^2} = kg \ m^{-1}s^{-2}$
Also, pressure is measured in Pascal $(Pa)$.
Multiple choice physics measurements and units measurement of area and volume measurement of volume measurement of area, volume and density

There are $n\ sets$ of real numbers. In every set there are four real numbers in AP. Such that the square of the last term is equal to the sum of the square of the first three terms. Then: -

  1. $N = 4$
  2. $N = 1000$
  3. $N = 10$
  4. $N \rightarrow \infty$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Let the terms of the AP be a - 3d, a - d, a + d, a + 3d (or standard a, a+d, a+2d, a+3d). Setting up the given condition that the square of the last term equals the sum of squares of the first three terms leads to a quadratic in terms of common difference or number of valid sets, which can be extended infinitely as parameters vary, yielding N -> infinity.

Multiple choice physics measurements and units measurement of area and volume measurement of volume measurement of area, volume and density

Four  positive charges $ ( 2 \sqrt 2-1 )Q $ are arranged at corner of square . another charge q is placed at the centre of the square. resultant force acting on each corner is zero if q is :

  1. $-7Q/4$
  2. $-4Q/ 7$
  3. $-Q$
  4. $none$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

For the resultant force on each corner charge to be zero, the electrostatic force due to the central charge q must balance the repulsive forces from the other three corner charges. Calculating the vector components along the diagonal yields q = -7Q/4.

Multiple choice physics measurements and units measurement of area and volume measurement of volume measurement of area, volume and density

A public park, in the form of a square, has an area of $(100 \pm 0.2 )m^2 $ .The side of park is :

  1. $ (10 \pm 0.01 ) m $
  2. $ (10 \pm 0.1 ) m $
  3. $ (10 \pm 0.02 ) m $
  4. $ (10 \pm 0.2 ) m $
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Let the side length of the square park is $l$.

The area of a square is given as,

$A = {l^2}$

$100 = {l^2}$

$l = 10\;{\rm{m}}$

The error in length is given as,

$\dfrac{{\Delta A}}{A} = 2\dfrac{{\Delta l}}{l}$

$\dfrac{{0.2}}{{100}} = 2\dfrac{{\Delta l}}{{10}}$

$\Delta l = 0.01\;{\rm{m}}$

Thus, the side of the park is $\left( {10 \pm 0.01} \right)\;{\rm{m}}$.

Multiple choice physics measurements and units summary of si units fundamental quantities system of units

In International System of units, there are seven base quantities whose units are defined. Which physical quantity has a prefix with its unit?

  1. Mass

  2. Thermodynamic temperature

  3. Luminous intensity

  4. Amount of substance
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Unit of mass is kilogram and here, kilo is a prefix used in the unit. Thus mass is the physical quantity which has prefix with its unit.