Tag: dynamics - explaining motion

Questions Related to dynamics - explaining motion

1 kilometer is ____ decimeter.

  1. $10^{4}$

  2. $10^{5}$

  3. $10^{3}$

  4. $10^{6}$


Correct Option: A
Explanation:

$1$ kilometer $=10^3$ meter and $1$ decimeter $=10^{-1}$ meter

So, $10$ decimeter $=1$ meter
Thus, $10^3 $ meter $=10^3\times 10$ decimeter $=10^4$ decimeter
or, $1$ kilometer $=10^4$ decimeter

1 nanometer is ___ femtometer.

  1. $10^{5}$

  2. $10^{6}$

  3. $10^{7}$

  4. $10^{4}$


Correct Option: B
Explanation:

$1$ nanometer $=10^{-9}$ meter and $1$ femtometer $=10^{-15}$ meter

So, $1$ femtometer $=10^{-6}\times 10^{-9}$ meter $=10^{-6}$ nanometer
So, $1$ namometer $=10^6$ femtometer

1 yotta is ____ yocto

  1. $10^{48}$

  2. $10^{-48}$

  3. $10^{47}$

  4. $10^{49}$


Correct Option: A
Explanation:

Yotta is the largest decimal unit prefix and yocto is the smallest decimal unit prefix in the metric system. 

$1$ yotta $=10^{24}$ meter and $1$ yocto $=10^{-24}$ meter
So, $1$ yotta $=10^{24}\times \dfrac{10^{-24}}{10^{-24}}$ meter $=\dfrac{10^{24}}{10^{-24}}\times 1$ yocto $=10^{48}$ yocto

1 millimeter is ____ terameter.

  1. $10^{-15}$

  2. $10^{-14}$

  3. $10^{-13}$

  4. $10^{-16}$


Correct Option: A
Explanation:

$1$ milimeter $=10^{-3}$ meter and $1$ terameter $=10^{12}$ meter

So, $1$ milimeter $=10^{-3}\times \dfrac{10^{12}}{10^{12}}$ meter $=\dfrac{10^{-3}}{10^{12}}\times 1$ terameter $=10^{-15}$ terameter 

1 nanometer is ____ centimeter.

  1. $10^{-8}$

  2. $10^{-7}$

  3. $10^{-9}$

  4. $10^{-6}$


Correct Option: B
Explanation:

$1$ nanometer $=10^{-9}$ meter and $1$ centimeter $=10^{-2}$ meter

So, $1$ nanometer $=10^{-9}\times \dfrac{10^{-2}}{10^{-2}}$ meter $=\dfrac{10^{-9}}{10^{-2}}\times 1$ centimeter $=10^{-7}$ centimeter

1 MeV is equal to

  1. $1.6\times 10^{13} Joules$

  2. $1.6\times 10^{13} cal.$

  3. $1.6\times 10^{13} ergs$

  4. None of these


Correct Option: D
Explanation:

An electronvolt is a unit of energy equal to the work done on an electron accelerated through a potential difference of $1$ volt.


$1 eV=1.6\times10^{-19}\ J$ 

$\therefore1\,MeV=1.6\times 10^{-19}\times10^{6}\,Joules$

$1\ MeV=1.6\times10^{-13}\ J$

Electron volt is the unit used to represent 

  1. energy

  2. power

  3. intensity

  4. charge of electron.


Correct Option: A
Explanation:

Electron volt, unit of energy commonly used in atomic and nuclear physics, equal to the energy gained by an electron (a charged particle carrying unit electronic charge) when the electrical potential at the electron increases by one volt. The electron volt equals $1.602\times 10^{-12}\,erg$  or  $1.602\times 10^{-19}\,joule$.

If the units of length and force are increased four times, then unit of energy will

  1. becomes 8 times

  2. becomes 16 times

  3. decrease 16 times

  4. increase 4 times


Correct Option: B
Explanation:

Unit of Energy $= kg. m^2/ s^2$

Unit of Force $= kg. m/s^2$

Unit of Length $= m$

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

Unit of Energy $= (kg. m/s^2) \times (m)$

If the units of length and force are increased by four times,

the unit of energy will be:

Unit of Energy $= (4 .kg. m/s^2) \times (4m)$

Unit of Energy $= 16 (kg. m^2/s^2)$

Therefore, if the units of length and force are increased by four times, the unit of energy will change by $16$ times.

If 1 mg $ns^{-1}$ = $10^x \mu g ps^{-1}$, then the value of x is _________.

  1. 1

  2. 2

  3. -1

  4. 0


Correct Option: D
Explanation:
We know that
$1\ mg=10^3\ \mu g$
$1\ ns=10^3\ ps$

Therefore, it can be written as:
$1mgn{ s }^{ -1 }={ 10 }^{ 3 }\mu gn{ s }^{ -1 }$

$ =\dfrac { { 10 }^{ 3 } }{ { 10 }^{ 3 } } \mu gp{ s }^{ -1 }$

$ ={ 10 }^{ 0 }\mu gp{ s }^{ -1 }\\ \Rightarrow x=0$
State whether true or false.
One mega watt is 10 times that of one kilowatt.
  1. True

  2. False


Correct Option: B
Explanation:
Mega is a prefix used for a factor of $10^6$.
Thus  $1 \ mega \ watt = 10^6 \ watt$
So, the given statement is false.