F ∝ dp / dt [ Greater the change in momentum , greater is force ] F = k dp / dt F = dp / dt F = d / dt ( mv ) Let , m : mass of the body be constant F = m dv / dt F = ma o
Newton ’ s Second law is consistent with the First law F = ma If F = 0 , then a = 0 According to First law , if a = 0 , Then F = 0 Thus , both the laws are in sync .
o
Vector form of Newton ’ s Second law
Fx = dpx / dt = max
Fy = dpy / dt = may
Fz = dpz / dt = maz o
Newton ’ s Second Law was defined for point objects . For larger bodies ,
o a : acceleration of the centre of mass of the system . o F : total external force on the system .