Question

A force produces an acceleration of $5.0cm{s}^{-2}$ when it acts on a body of mass 20 g. The force in newton is:

• A. $2\times {10}^{-3}N$
  
• B. $4\times {10}^{-3}N$
  
• C. $1.0\times {10}^{-3}N$
  
• D. $5\times {10}^{-3}N$

Answer 1

The correct option is C $1.0\times {10}^{-3}N$


Given mass, $m=20g$ and acceleration , $a=5.0cm{s}^{-2}$
Let the force be $F$.
We know, $F=ma=20\times 5=100gcm{s}^{-2}=\text{100 Dyne}$.
The cgs unit of force is $gcm{s}^{-2}$, also known as Dyne.
The relationship between cgs unit Dyne and SI unit Newton is
$1Dyne={10}^{-5}N$
$\therefore F=100\times {10}^{-5}=1\times {10}^{-3}N$