What are some examples of parabolas?
Here are just two examples of parabola in physics.
Under ideal conditions a trajectory of an object thrown at an angle to a horizon is a parabola.
When light falls on a parabolic mirror parallel to its axis of symmetry, it is reflected by a mirror in such a way that all individual rays are intersecting in the focal point of a parabola.
Both cases can be proven analytically based on the definition and properties of parabola and laws of physics.