One of the endlessly fascinating things about physics is that it's in literally everything. Makeup is one of my primary hobbies, and I've noticed many aspects of physics in my daily routine.
Whether you're using a makeup brush or a makeup sponge to get that flawless finish, you create a lot of friction on your face. In fact, the level of friction you apply will determine the quality of your application. Not enough, and you'll look a patchy mess. Too much, and you probably irritate your skin and defeat the purpose. A perfect balance of friction is what will lead you to a soft blend.
Also, density plays a huge roll in makeup. When choosing between kinds of base makeup, from foundation to BB creams to tinted moisturizer, you have to know the kind of look you're going for. The denser the formula, the higher the coverage, and the thicker the finish.
On a semi-related beauty note, static electricity is also a common battle in hair. This doesn't affect everyone, but being someone who has thick curly hair, I know too well the pain of having to carry dryer sheets to calm staticy hair.
Lastly, every makeup lovers worst fear is gravity. The unfortunate acceleration due to gravity on all objects is never more real than when a compact or favorite pressed pigment slips from your hand and plummets to the ground. Seeing the powder shatter truly is a tragic moment, causing you to curse gravity. Everything is physics, and it can be fun to notice it in simple daily tasks.