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

$1.0\times {10}^{-3}N$

F= ma = $20\times 5=100$ dynes.
$But1dyne={10}^{-5}N$
$\therefore F=100\times {10}^{-5}N=1\times {10}^{-3}N$