A mirror is a reflective surface. A lens, on the other hand, does not reflect light; it refracts it

In physics, fluid dynamics is a sub discipline of fluid mechanics that deals with fluid flow—the natural science of fluids (liquids and gases) in motion.

Thermal expansion is the tendency of matter to change in volume in response to a change in temperature

In physics a force field is a vector field that describes a non-contact force acting on a particle at various positions in space.

Archimedes' principle is a law of physics stating that the upward buoyant force exerted on a body immersed in a fluid is equal to the weight of the fluid the body displaces. In other words, an immersed object is buoyed up by a force equal to the weight of the fluid it actually displaces.