469.24m. An airplane flying 60m/s at a height of 300m dropped a sack of flour that stack the ground 469.24m from the point of release.
This is a example of horizontal parabolic projectile motion,and we represents this motion in the coordinate axis, which means that the velocity has components in x axis and y axis.
The equation of components on the x axis.
, where x is the distance and Vox the initial velocity before the drop
The equation of components on the y axis.
, where y is the height, and the velocity in y component before the drop is 0, reducing the equation to 
Clear t from both the equation of components on the x axis and the y axis:
and 
Equating both equations and clearing the distance x:

Substituting the values:

200 miles from a nation's coast
A falling object will reach 49 m/s