The instantaneous velocity is the derivative of the position function s=f(t) with respect to time.At tiem t,the velocity is
V(t)=\(\frac{ds}{dt}=\lim_{x\rightarrow \Delta t } \frac{S(t+\Delta t)-S(t)}{\Delta t} \)
(1)v(t)=\(\frac{ds}{dt} t^2=2t\)
(2)\(\lim_{t\rightarrow 2} 2t=2*2=4\)
not good at calculus,might be wrong