To determine the drop height needed for a 420-pound weight to exert the same force as a 350-pound weight dropped from 5 feet, additional information is required, particularly regarding deceleration factors. Key variables include the elasticity of the harness, the supporting ropes, and the potential deformation of the human body upon impact. Accurate calculations may be challenging and often rely on experimental data gathered from accelerometers in mannequins or cadavers. If both weights use identical harnesses and cables, a rough estimate could be possible. Understanding these dynamics is crucial for safety in harness testing.