Gist: When acceleration is constant, position is a quadratic in time — and the three coefficients turn out to be the initial position, the initial velocity, and half the acceleration.

Why it matters: Differentiate twice and the constants fall out with physical meaning attached. Worked in the lecture as , giving and — noted there as the shape of a single segment in motion planning.

Detail: Lecture 2, p.5

Related: Instantaneous acceleration, Free fall, Physics