This study presents the results of experimental investigations into the dynamic and energetic characteristics of a high-pressure water jet using high-speed imaging in conditions relevant to abrasive water jet machining (AWJ) applications. The scientific contribution of the work lies in the combined experimental determination of jet velocity and kinetic energy over a wide operating pressure range, together with a direct comparison between measured jet characteristics and a simplified Bernoulli-based analytical model. The aim of the study was to determine jet velocity at different operating pressure levels, evaluate the corresponding kinetic energy, and compare the experimental results with theoretical values calculated using a simplified Bernoulli-based model. The experiments were carried out on an Eckert Combo machine using a Phantom V1610 high-speed camera. Measurements were performed for five operating pressure levels: 50, 100, 200, 300, and 380 MPa. The recorded video sequences were analyzed in TemaMotion software, which made it possible to determine the displacement, velocity, and acceleration histories of a characteristic point of the jet, as well as the mean values of experimental jet velocity. The experimental velocity increased from 144 m/s at 50 MPa to 430 m/s at 380 MPa, while the corresponding theoretical values ranged from 316.23 m/s to 871.78 m/s. The relative deviation between the experimental and theoretical results ranged from -39.92% to -54.46%. On this basis, the kinetic energy of the jet was determined and was found to increase from 0.00814 J to 0.07260 J for the experimental data and from 0.03927 J to 0.29845 J for the theoretical model. The obtained results indicate that operating pressure significantly affects the dynamic response and energy potential of the water jet, with the increase in kinetic energy representing the most important effect from the standpoint of its technological potential. The results also show that kinetic energy provides a more informative measure of the technological potential of the jet than velocity alone, while at the same time revealing the limitations of the idealized Bernoulli-based description under real experimental conditions. In this way, the study contributes to a more quantitative understanding of pressure-dependent jet behavior in systems relevant to AWJ applications.