A 3.3 kg brick is falling at a rate of 35.1 m/s toward the earth at a current height of 14 m. What is the total mechanical energy of the brick?

Answer 1

Using a potential energy datum plane at ground level, the total mechanical energh at that time is
(1/2) M V^2 + M g H,
where H = 14m.

The location of a reference "datum" plane for zero potential energy is arbitrary. It is only changes in P.E. that matter.