  Extracting the rotational energy from a Kerr black hole (BH) is one of the
crucial topics in relativistic astrophysics. Here, we give special attention to
the Penrose ballistic process based on the fission of a massive particle
$\mu_0$ into two particles $\mu_1$ and $\mu_2$, occurring in the ergosphere of
a Kerr BH. Bardeen et al. indicated that for the process to occur, some
additional "{\it hydrodynamical forces or superstrong radiation reactions}"
were needed. Wald and Chandrasekhar further expanded this idea. This animosity
convinced T. Piran and collaborators to move from a simple three-body system
characterizing the original Penrose process to a many-body system. This
many-body approach was further largely expanded by others, some questionable in
their validity. Here, we return to the simplest original Penrose process and
show that the solution of the equations of motion, imposing the turning point
condition on their trajectories, leads to the rotational energy extraction from
the BH expected by Penrose. The efficiency of energy extraction by a single
process is quantified for three different single decay processes occurring
respectively at $r=1.2 M$, $r=1.5 M$, and $r=1.9 M$. An interesting repetitive
model has been proposed by Misner, Thorne \& Wheeler \citep[][hereafter
MTW73]{Misner:1973prb}. Indeed, it would appear that a repetitive sequence of
$246$ decays of the above injection process at $r=1.2 M$ and the corresponding
ones at $r=1.5 M$ and $r=1.9 M$ could extract $100\%$ of the rotational energy
of the BH, so violating energy conservation. The accompanying paper, accounting
for the existence of the BH irreducible mass, introduces a non-linear approach
that avoids violating energy conservation and leads to a new energy extraction
process.
