What? Physics is not a branch of mathematics, it just uses mathematics and mathematical properties. That's like saying psychology is a branch of mathematics because it involves statistics. Using math isn't the same as being math. Admittedly physics is one of the "mathiest" fields, but it still involves doing experiments and coming up with mathematical models that fit the data rather than coming up new kinds of mathematics. The line was much more blurred in Newton's time, but these days the distinction is pretty obvious.