Tag: dynamics - explaining motion

Questions Related to dynamics - explaining motion

In particular system of unit, if the unit of mass becomes twice and that of time becomes half, then $8$ Joules will be written as _______ units of work

physics dynamics - explaining motion physical quantities motion and measurement units - definitions and systems

  1. $16$

  2. $1$

  3. $4$

  4. $64$

Show answer
Correct Option: D
Explanation:
The unit of work is $kg\ m^2/s^2$.

$8Joule=\dfrac { 8M{ L }^{ 2 } }{ { T }^{ 2 } }$

$ =\dfrac { 8(1kg){ (1m) }^{ 2 } }{ { (1s) }^{ 2 } } $

On doubling the unit of mass and unit of time is halved:
$=\cfrac { 8(2\quad unit\quad of\quad mass){ (1m) }^{ 2 } }{ { \left( \frac { 1 }{ 2 } unit\quad of\quad time \right)  }^{ 2 } }$

$ =\dfrac { 8\times 2 }{ { \left( \frac { 1 }{ 2 }  \right)  }^{ 2 } } units\quad of\quad work\\ =64\ units\quad of\quad work.$