The three equations are: $$v = u+ at  , $$$$s = ut + \dfrac{1}{2} at^2  , $$$$ v^2 = u^2 + 2as.$$  Can I use them for both finding instantaneous and average quantities? Suppose I want to find the final instantaneous velocity then can I use the first equation or if I want to find average velocity over a time period, can I use the 1st equation? Plz explain me elaborately.