prove that impulse is equal to the change in momentum
By definition of impulse
I = F∆t
Now again,
F = ma
a = (v-u)/ ∆t
=> F = m(v-u)/ ∆t
=> F ∆t = m(v-u)
=> I = mv – mu
But mv = final momentum (pf )
And mu = initial momentum (pi)
=> I = pf – pi
=> I = ∆p
Thus impulse is change in momentum, proved.