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Discussion Response Post to: how does newton's 1st & 3rd law follow from newton's 2nd law?

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14 Mar 2008 19:12:44 IST

Subject: how does newton's 1st & 3rd law follow from newton's 2nd law?

netkid07 (2019)

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frm 2nd law...........F=ma
so

if F=0 then and only then a=0.............which is first law !!

also frm 2nd law

dP/dt=F

consider a 2 body system

F12=dP1/dt (force on 1st body due to 2nd body).............(1)

F21=dP2/dt (force on 2nd body due to 1st body).............(2)

adding (1) and (2)

F12+F21=d(P1+P2)/dt

but if no external force is acting then change in momentum of system is zero so

F12= - F21 (third law)

hope it helps !!.....cheers

Who says nothing is impossible.

I've been doing nothing for years !!..............

I know KUNG FU KARATE
and 47 other dangerous words.............

this reply: 7 points (with 1 Olaaa!! Perrrfect answer.

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