What do we mean by derivative of a function? What does it tell? Taking the derivative of any kind of function is easy but I don't know why we take the derivative? Like     $f(x)=x^2$   has the derivative   $2x$,   so what does it mean? I don't know how to define dy/dx? Understanding derivative and Integral in terms of physics becomes hard. Like [here]: () edit: I don't think it's a duplicate of other question. I've studied Derivative and Integral in maths but when it comes to physics it needs to have concept in our mind. Like this
Simple way to understand what derivative is I know how to count derivatives, but I actually don't understand what are those? What do they show?   Wikipedia explanation: Loosely speaking, a derivative can be thought of as how much one quantity is changing in response to changes in some other quantity. I understand nothing what is written here?  Please, if you can, explain me as simple as you can it. Thank you very much.
Book recommendations for fluid dynamics self-study I have my bachelors degree in engineering science: computer science, option electrotechnic. I have a good understanding of basic mechanics and dynamics, calculus (differential equations).  The books I'm now having a look at are:       What book do you recommend for studying fluid dynamics on my own and why?