Question

Prove second law of motion with the help of first and third law of motion.​

Answer 1

Answer:

Answer

Newton's second law of motion is F=ma

That is we have:-

F=m(v−tu) thus, Ft=mv−mu.

Now,When F=0, then v=u. That is the absence of force,The object continue to move with same velocity

throughout.

Now,when F=0 and u=0, then v=0. That is , an object at rest if no force is acting on it.

Thus,

Newton's first law is derived from the second law.

Now let us consider a system of 2 bodies 1&2 and considers that there is no external force acting.

 Now let F12 be the force acting on 2 by 1 and F21 be the force acting on 1 by 2.

The rate of change of momentum of 1=dtdp1 and rate of change of momentum of 2=dtdp2

Thus, according to Newton second law of motion F12=dtdp2 and F21=dtdp1

Adding both the above equation, we get:-

F12+F21=dtdp2+dtdp1=d(p2