Tutor profile: Edward Z.

Can you describe to me what Reynolds number is or what it means? What does it describe?

Reynolds number is the ratio of inertial and the viscous forces. Basically it is telling you which forces dominate the flow. This number vastly changes the physics we use to describe flow and most things except for microscopic organisms have a Reynolds numbers greater than 1. It's mainly used to describe the flow regime that you are in (turbulent, laminar, transition).

What is the easiest way to break down any mechanical system?

By drawing a free body diagram and then making assumptions about the system and finally defining the forces using those assumptions.

How would you describe the derivative of your happiness?

You would describe as if you are getting happier or sadder everyday. If your level of happiness isn't changing at all then its zero.