Are some laws in physics really as simple as they seem?

For example, is $F = ma$ really an exact formula, or is it an approximation? I know a lot of formula's come from taking the first few terms of a Taylor expansion, so I was wondering if the simple formulas such as the one stated are exact or approximations.

• Every single equation you ever see in science is an approximation. Every single statement ever made comes with error bars. Don't confuse the equation for reality! The universe isn't made of math (I think), and the equations are what we use to describe our observations of the universe. The equations are ours, not the universe's. The universe just does what it does. – march Nov 11 '15 at 22:45

For example as stated in the answer of Dirk Bruere, relativistic effects occur near the speed of light, so for a lot of practical applications on Earth $F=ma$ will still be a very good approximation. Also general relativity turns out to better predict the motion of planets then Newtonian gravity 