# Why do we need lots of mechanics? [closed]

I think every motions could be determined by Newtonian Mechanics, but why do we need rotational mechanics, or fluid mechanics?

• Re I think every motions could be determined by Newtonian Mechanics - This question was asked and answered over 100 years ago, and the answer is no. Re why do we need rotational mechanics, or fluid mechanics? Because those are important phenomena. Jun 2, 2018 at 10:37

Sure, you can describe the motion of each point using linear mechanics, using just F=ma, but now each point has a different acceleration, and you don't have a nice way to describe the motion of the whole wheel. Rotational mechanics introduces angular acceleration and lets you say $\tau=m\alpha$, which describes the whole wheel very nicely.