Tag: dynamics - explaining motion

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Questions Related to dynamics - explaining motion

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

Which of the following is used as SI prefixes:

  1. Micro

  2. Mica

  3. Mikro

  4. Maca
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Micro is a prefix used in defining some units.  Whenever the word micro is attached as a prefix to an SI unit,  it means it is one million times smaller than that unit. For example, 1 micrometre is one millionth part of a metre. Rest all other options are not   prefixes 

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

If the values of force and length are increased four times, then the unit of energy will be increase by:

  1. 4 times

  2. 2 times

  3. 8 times

  4. 16 times
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
The correct option is D
We have, $f=4[MLT^{-2}]$ and $d=4[L]$

$E=f\times d$

We know that Energy is equal to the product of force and distance.

Thus,
$=4[MLT^{-2}]\times4[L]$

$=16[ML^2T^{-2}]$

If both increased by 4times then the energy increased by $16\ times$
Multiple choice physics dynamics - explaining motion system of unit summary of si units system of units

If unit of mass, length and time are tripled, then unit of energy becomes:

  1. $3$
  2. $\dfrac{1}{3}$
  3. $9$
  4. $\dfrac{1}{9}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Unit of Energy $kg\,m^2/s^2$

Unit of length $= m$ (metre)

Unit of mass $= kg$ (kilogram)

Unit of time $= s$ (second)


Thus unit of energy in terms of unit of mass, length and time is given by,

$Unit \,of\, Energy =\dfrac{(Unit\,of\,mass)\times(Unit\,of\,length)^2}{(Unit\,of\,time)^2}$

If the unit of mass, length and time are tripled the unit of energy will be,

$Unit \,of\, Energy =\dfrac{(3\times Unit\,of\,mass)\times(3\times Unit\,of\,length)^2}{(3\times Unit\,of\,time)^2}$

$Unit \,of\, Energy =3\times \dfrac{(Unit\,of\,mass)\times(Unit\,of\,length)^2}{(Unit\,of\,time)^2}$

$Unit\,of\,energy=3\times Unit\,of\,energy$

Therefore, if the unit of mass, length and time are tripled, the unit of energy will be, 3 times more than the original unit of energy.
Multiple choice physics dynamics - explaining motion system of unit summary of si units system of units

If a thermometer reads freezing point of water at 20 degree Celsius and boiling point as 150 degree Celsius, how much thermometer can read when the actual temperature is 60 degree Celsius?

  1. 98 degrees celsius

  2. 10 degree Celsius

  3. 40 degree Celsius

  4. 60 degree Celsius
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Using linear interpolation: (T - 20) / (150 - 20) = (60 - 0) / (100 - 0). (T - 20) / 130 = 60 / 100 = 0.6. T - 20 = 78, so T = 98.