Scientific reading and explanation
Build an initial energy budget
An object released from rest at initial height H has initial gravitational potential energy U_0=mgH, relative to a floor reference. For the ideal fall from H to h without drag or losses, its kinetic energy at h is K=mg(H−h), while potential energy is U=mgh. Their sum remains mgH. This model assumes the same g at both heights.
Speed from released energy
Since K=½mv², the ideal speed magnitude at height h is v=√(2g(H−h)). Mass cancels in the ideal fall-from-rest formula; that cancellation is not evidence that real-world air drag affects all shapes identically. At H=5 m and h=3 m, released energy per kg is 19.6 J/kg, giving speed √39.2≈6.26 m/s.
Add transfers without losing energy
With air resistance, some initially stored gravitational energy is transferred to thermal/internal energy of the surroundings, air and object. In this lab we specify a fraction f of released energy as the nonmechanical transfer: E_other=fmg(H−h). The remaining kinetic energy is K=(1−f)mg(H−h). Then U+K+E_other=mgH. This prescribed fraction is a mathematical teaching model, not a real drag law.
Stop before contact
The model predicts a state just before any contact at h=0; it does not predict what happens during impact. The speed is a magnitude, not a signed vertical velocity. Dropping real objects from height is unnecessary; students should use virtual outputs and the printable calculated dataset.