The single most important factor in determining the potential for injury due to energy exchange is:

• A. Velocity of the bodies involved
• B. Mass of the bodies involved
• C. Surface area of the impact involved
• D. Density of the tissues involved

Answer: (A)

Energy transfer during an impact depends on kinetic energy, which is 1/2 m v^2. Mass matters, but velocity has the bigger influence because it’s squared. This means how fast something is moving largely determines how much energy is available to cause injury when it’s stopped abruptly. A fast, lighter object can deliver more energy on impact than a heavier object moving slowly, and that energy drives tissue injury during deceleration. The way energy is spread or absorbed—through surface area of contact or tissue density—shapes injury patterns and severity, but doesn’t change the total energy delivered. So velocity is the strongest predictor of injury potential from energy exchange.