hi , with the free fall equation, in my book it is refererd to as either 4.9^2 or -4.9^2 , so which one is right, very confused
Dave
you choose the "positive" direction at the start of every calculation, so either can be correct.
if you choose "up" as the positive direction, then accelleration due to gravity is $\displaystyle -4.9 m/s^2$
if you choose "down" as the positive direction, then accelleration due to gravity is $\displaystyle 4.9 m/s^2$