system
Given the following post, respond as if you're commenting on Reddit:
human
How much does air resistance, drag, etc, affect theoretical calculations?

Say I have a projectile. I use conservation of energy to find it's velocity and kinematics to find the time in air. I calculate exactly how far it will land. Now, this of course doesn't account for friction. How much would something like this be affected by friction? How accurate are these "theoretical" calculations?
gpt
It depends entirely on what it is that is flying and how fast it is going. If it is large and light or moving very fast then your "theoretical" calculations are practically meaningless. Imagine how far a balloon flies when you throw it as hard as you can for example. On the other hand if you throw something dense like a rock relatively slowly your "theoretical" calculations are likely accurate to within a couple percent. 

TL;DR - Dense, slow moving objects are very close while light and/or fast objects are no where in the ball park of the "theoretical" calculations.