Real simple one

Depends on how long it accelerates, and what the initial velocity is. When all you know is an instantaneous acceleration value the problem is under-defined.

ok, thanks, that would explain why i couldn't find any info

But the moment you throw it in the air, the only force (well, in a simple physics question that ignores stuff like drag and the effect of wind, etc.) affecting it is gravity so where is that acceleration coming from? All you need to know is the initial velocity and solve it from there. Or am I missing something?

shmoove

The following frictionless projectile formulas may help you (these can be found in any textbook or google for projectile motion):

1) s = ( u * t ) + ( 0.5f * a * ( t * t ) )
2) v = u + ( a * t )

where

* = multiply
s = distance travelled in meters
u = initial velocity in meters per second
v = current velocity in meters per second
t = time in seconds
a = acceleration in meters per second squared


If you know the initial velocity upwards (u) and constant gravity (g) is acting downwards then the time it is in the air can be derived like so:

We know that the velocity when the object arrives at the starting position again (end of arc) is -u and acceleration is -g. Substitute into 2) gives:

-u = u + ( -g * t )

-2 * u = -g * t

which gives:

t = ( 2 * u ) / g


Hope that helps.