Answer the following questions related to the logical basis of the equations of motion for uniformly accelerated straight-line motion.
(i) Define acceleration and write its SI unit.
(ii) State the specific assumption about acceleration that is made while deriving the standard three equations of motion. Why is this assumption essential?
(iii) While deriving the second equation of motion, the idea of average velocity is used. Explain what is meant by average velocity in this context and how it links initial velocity, final velocity and displacement for constant acceleration.