Function initial_kinetic_energy_from_work 

pub fn initial_kinetic_energy_from_work(
    final_kinetic_energy: f64,
    work: f64,
) -> Option<f64>

Computes initial kinetic energy from a final kinetic energy and applied work.

Formula: KE_initial = KE_final - W

Returns None when final_kinetic_energy is negative, when any input is not finite, when the computed result is negative, or when the computed result is not finite.