There are many ways to do it. This is what i did for testing...
Code:
var earthgravity[3] = 0,0, -386;
var bulletspeed;
function physic_setup()
{
ph_setgravity( earth_gravity );
ph_selectgroup(1);
}
action Item_Object
{
object = me;
phent_settype( object, PH_RIGID, PH_BOX );
phent_setmass(my, 1, PH_SPHERE);
phent_setfriction(my,0);
phent_setdamping(object, 0.1,0.1);
phent_setgroup( object, 1 );
ph_selectgroup(1);
phent_addforcelocal(my, bulletSpeed, nullvector);
}