physics can be found in everything, even the weather!! All precipitation contains elements of physics, however rain is perhaps the most interesting. Rain falls at what is called terminal velocity. this is when an object reaches a cirten speed and stops accelerating. The acceleration around earth is 9.81 meters per second^2. There is a very interesting physics consept as to why the rain water doesnt have a more devistating effect.
most rain drops fall at a velocity of about 18 mph. getting hit with a rock going this speed would be a much different experience than being hit with a rain drop. the reason rain drops arent painful is due to the fact that they have a smaller mass. getting hit with a 4kg rock is a greater force, this is because the force is equal to the mass multiplied by the acceleration (g). Because the rain drops have a next to negligable masses the force that they impact earth with is very little and therefore doesnt cause more damage when it impacts earth.
the shape of a rain drop is also an interesting and under studied phenominon. they are not tear drop shaped, but instead most of them look like small flattened hamburger buns. this is due to their size, bigger or smaller rain drops actually for different shapes depending on their air resistance due to their sizes. overall, rain is just an example of how almost every aspect of our world is determined by physics, even mother natures miracles!