Reduce the friction. Since the total energy is conserved, the only way to improve its work capacity is by reducing energy that doesnt go into work.
Answer:
Charge Z can be placed at <em>x</em> = -2.7 m or at <em>x</em> = 0.27 m.
Explanation:
The Coulomb force between two charges,
and
, separated by a distance,
, is given

<em>k</em> is a constant.
For the charge Z to be at equilibrium, the force exerted on it by charge X must be equal and opposite to the force exerted on it by charge Y.
It is to be placed along the <em>x</em>-axis. Hence, it is on the same line as charges X and Y.
Let the charge on Z be <em>Q</em>. It is positive.
Let the distance from charge X be <em>x m.</em> Then the distance from charge Y will be (0.60 - <em>x</em>) m.
Force due to charge X

Force due to charge Y

Since both forces are equal and opposite,







Applying the quadratic formula,

or 
Charge Z can be placed at <em>x</em> = -2.7 m or at <em>x</em> = 0.27 m
The force of gravity is the
force with which massively large objects such as the earth attracts another
object towards itself. All objects of the earth exert a gravity that is
directed towards the center of the earth. Therefore, the force of gravity of
the earth is equal to the mass of the object times acceleration due to gravity and also equal to the weight of the object.
F = ma
since F = W
W = ma