Question

how will you find average velocity ,if acceleration is
(i) uniform
(ii) non -uniform

Answer 1

distance by time in uniform
distance into time in non uniform

Answer 2

$\text{Average velocity, }\langle v \rangle\\=\frac{\text{Total Distance}}{\text{Total Time}}\\=\dfrac{\int_{0}^{t}vdt}{t}\\=\dfrac{\text{Area of v-t graph measured from t=0 to t=t}}{t}$
This formula works for both uniform as well as non uniform acceleration.For uniform acceleration, you can prove it to be $\frac{v+u}{2}.$For non-uniform, either calculate the area of v-t graph and divide it by time or integrate velocity as a function of time.