Conservation of Energy Formula: A Rock Falling from a 20 m Cliff

The original prompt itself states only the rock’s mass, the 20 m cliff, and the 10 m fall. The textbook’s worked solution then lists $v_1=0$ and $g=9.80,mathrm{m/s^2}$, and the surrounding section uses a frictionless approximation for these mechanical-energy transformations. The calculation follows that textbook model; with significant dissipative work, mechanical energy alone would not remain constant.