What principle states that internal pressure decreases at points where speed increases?

Bernoulli's Principle is key in understanding how fluid dynamics work, particularly in the context of aviation and how airflow behaves over wings and other surfaces. This principle states that in a streamlined flow, an increase in the speed of the fluid occurs simultaneously with a decrease in pressure or potential energy. In practical terms, as the air moves faster over a surface (such as the wing of an aircraft), the internal pressure in that faster-moving area drops compared to the surrounding slower-moving air. This pressure difference is what creates lift, allowing airplanes to fly.

The other principles listed do not relate to the changes in pressure and velocity of fluids. Newton's Law relates to motion and forces, Charles' Law deals with the relationship between temperature and volume of gases, while Hooke's Law pertains to the elasticity of materials. Each of these laws addresses different physical phenomena that do not involve the same interactions between speed and pressure in fluid dynamics that Bernoulli's Principle describes.