Free Fall

Free fall is motion under gravity alone (ignoring air resistance).

Acceleration = g = 9.8 m/s² downward (≈10 m/s² for quick estimates).

From rest at height h: fall time t = √(2h/g); impact speed v = √(2gh).

Thrown up with speed u: max height = u²/(2g); time up = u/g; total flight = 2u/g.