Question

State Newton's second law of motion. Use this law to find the method to measure forces acting on an object.

Answer 1

Newton's second law of motion:

According to Newton's second law of motion, the rate of change of momentum of a body is directly proportional to the net force acting on it. Momentum is defined as the product of mass and velocity.

Finding force

$$\begin{gathered} Force\propto Rateofchangeofmomentum \\ Force\propto \frac{(Finalmomentum-Initialmomentum)}{time} \\ F\propto \frac{(mv-mu)}{t} \\ Where, \\ m-massofanobject, \\ u-initialvelocity, \\ v-finalvelocity, \\ t-time \\ F\propto \frac{m(v-u)}{t} \\ F\propto ma \\ F=kma \\ Theunitofforceischoseninsuchamannerthatthecons\tan tofproportionalitykbecomesone \\ If,k=1 \\ F=ma \end{gathered}$$

Hence, by the expression, $F=ma$ we can measure forces acting on a body.