1. Foundation: Fluid mechanics is a subject that needs a lot of mathematical knowledge, such as differential equations and matrices, and it is very difficult.

Many concepts and principles involved in fluid mechanics, such as fluid viscosity, fluid pressure distribution, application of Bernoulli equation, etc.

2. Learning: Fluid mechanics is abstract, including water and air. Learn the laws of mechanical motion of fluids (liquids and gases) and their applications. Through systematic study and continuous practice, most students can master the basic knowledge of fluid mechanics and apply it to practical problems. So fluid mechanics is very difficult.