Tag: summary of si units

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Multiple choice physics dynamics - explaining motion system of unit summary of si units system of units

$S = A(1 - e^{-Bxt})$, where S is speed and x is displacement. The unit of B is :

  1. $m^{-1}s^{-1}$

  2. $m^{-2}s$

  3. $s^{-2}$

  4. $s^{-1}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

It is given that $x$ is displacement and $t$ is time.
Unit of $x$ is $m$ and that of time t is $s$.
Since, the quantity $Bxt$ must be dimensionless.
$\implies$ Unit of B must be $m^{-1}s^{-1}$.

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.

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

Force F  and density d are related as F is equal to A divided by B plus root d obtain dimensions of A

  1. $M^ \dfrac{3}{2} L ^ {\dfrac{-1}{2} }T^{-2}$

  2. $M^ \dfrac{3}{2} L ^ {\dfrac{-1}{2} }T ^ {2}$

  3. $M^ \dfrac{3}{2} L ^ {\dfrac{1}{2} }T ^ {2}$

  4. $M^ \dfrac{3}{2} L ^ {\dfrac{5}{2} }T ^ {-2}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Given F = A / (B + sqrt(d)), for the equation to be dimensionally consistent, B must have the same dimensions as sqrt(d), which is (ML^-3)^0.5 = M^0.5 L^-1.5. Since F = [MLT^-2], then A = F * (B + sqrt(d)) = [MLT^-2] * [M^0.5 L^-1.5] = M^1.5 L^-0.5 T^-2.