# free fall equation

• March 24th 2012, 02:37 PM
davellew69
free fall equation
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
• March 24th 2012, 03:11 PM
SpringFan25
Re: free fall equation
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 $-4.9 m/s^2$

if you choose "down" as the positive direction, then accelleration due to gravity is $4.9 m/s^2$
• March 24th 2012, 03:13 PM
davellew69
Re: free fall equation
what is ment by up or down as the positive direction?