In this study two-dimensional physical and finite element models of human head under linear deceleration were developed. 5% gelatin was used as the brain substitute material with similar viscoelastic properties. The experimental strains and pressure during 55G impacts were measured to validate the element formulations used in the computational models. The Lagrangian and Arbitrary Lagrangian Eulerian (ALE) formulations were used in the FE models. It was shown that without Cerebrospinal Fluid (CSF), the Lagrangian strains passed the 10% threshold of axonal injury. At the presence of CSF, no significant strain was observed while 6 to 8 times increase in the intracranial pressure was recorded. The FE models showed similar trends for strain, stress, and pressure but were generally more aggressive than the experimental results. The ALE model was more stable and its effective damping was more consistent with the experimental data.