Answer:
The net force is the vector sum of all the forces that act upon an object. That is to say, the net force is the sum of all the forces, taking into account the fact that a force is a vector and two forces of equal magnitude and opposite direction will cancel each other out.
Explanation:
put in your own words PLEASE, hope it helps
Well the trivial answer is zero, since there is indeed a "zero vector". Assuming you aren't allowed to use the zero vector you would need at least two. They would be antiparallel and of equal magnitude. (That is be pointing in opposite directions and have the same length)
The closer you are to the ground the more accurate you'll be. That's why most snipers are in the "prone" position.
Let both the balls have the same mass equals to m.
Let
and
be the speed of the ball1 and the ball2 respectively, such that

Assuming that both the balls are at the same level with respect to the ground, so let h be the height from the ground.
The total energy of ball1= Kinetic energy of ball1 + Potential energy of ball1. The Kinetic energy of any object moving with speed,
, is 
and the potential energy is due to the change in height is
[where
is the acceleration due to gravity]
So, the total energy of ball1,

and the total energy of ball1,
.
Here, the potential energy for both the balls are the same, but the kinetic energy of the ball1 is higher the ball2 as the ball1 have the higher speed, refer equation (i)
So, 
Now, from equations (ii) and (iii)
The total energy of ball1 hi higher than the total energy of ball2.