Hi there!
Recall the equation for electric potential of a point charge:

V = Electric potential (V)
k = Coulomb's Constant(Nm²/C²)
Q = Charge (C)
r = distance (m)
We can begin by solving for the given electric potentials. Remember, charge must be accounted for. Electric potential is also a SCALAR quantity.
Upper right charge's potential:

Lower left charge's potential:

Add the two, and subtract from the total EP at the point:

The remaining charge must have a potential of 2036.25 V, so:

Answer: 3 m/s
Explanation:
We can solve the problem by using the law of conservation of momentum: during the collision between the two balls, the total momentum of the system before the collision and after the collision must be conserved:

The total momentum before the collision is given only by the cue ball, since the solid ball is initially at rest, therefore

So, the final total momentum will also be

And the total momentum after the collision is given only by the solid ball, since the cue ball is now at rest, therefore:

from which we find the velocity of the solid ball

Answer:
The strength of gravity decreases.
An example of that would be if you were in space; you float around because there's no gravity.
<h2>
Time taken is 0.459 seconds</h2>
Explanation:
We have equation of motion v = u + at
Initial velocity, u = 0 m/s
Final velocity, v = 81 km/hr = 22.5 m/s
Time, t = ?
Acceleration, a = 49 m/s²
Substituting
v = u + at
22.5 = 0 + 49 x t
t = 0.459 seconds
Time taken is 0.459 seconds
C because the stack of paper was divided into 4