Trauma Nurse Core Course (TNCC) Practice Exam

Which factor contributes the most to the kinetic energy of a body in motion?

1. Acceleration

2. Mass

3. Velocity

4. Inertia

The correct answer is: Velocity

The factor that contributes the most to the kinetic energy of a body in motion is velocity. Kinetic energy is mathematically defined by the equation KE = 1/2 mv², where m represents mass and v represents velocity. This equation illustrates that kinetic energy is proportional to the square of the object's velocity. Therefore, any increase in velocity has a significantly larger impact on the total kinetic energy than an equivalent increase in mass. While mass does play a role, velocity's squared influence means that it can contribute more dramatically to kinetic energy, especially at higher speeds. This is why in physics and trauma care assessments, understanding the velocity of a moving object is crucial when evaluating potential injury outcomes or the severity of trauma, as a higher velocity can lead to a greater kinetic energy transfer upon impact. Other factors related to motion, such as acceleration and inertia, are relevant in their contexts, but they do not directly determine the kinetic energy in the same potent manner as velocity.