Question

For the free fall formulas: y = y0 + v0t- 1/2gt^2, v = v0 - gt, and v^2 = v0^2 - 2g(y-y0), does one need to put a negative sign when inputing g? In short, would g = -9.8 or 9.8? It seems like the negative sign of gravitational acceleration is already accounted for in the equations.

Answer 1

Yea it is, so you have to choose your coordinates direction as assuming the direction of x+ and y+.

as coordinates isn't a real thing you just choose them to make calculation easier :D