I think its " both have level surfaces"
Answer:

Explanation:
Consider two particles are initially at rest.
Therefore,
the kinetic energy of the particles is zero.
That initial K.E. = 0
The relative velocity with which both the particles are approaching each other is Δv and their reduced masses are

now, since both the masses have mass m
therefore,

= m/2
The final K.E. of the particles is

Distance between two particles is d and the gravitational potential energy between them is given by

By law of conservation of energy we have

Now plugging the values we get



This the required relation between G,m and d
Answer:
Using the given values
F = K q^2 / r^2 = 9 * 10E9 * (1.6 * E-19)^2 / (5.18 * E-15)^2 N
E = 9 * 1.6^2 / 5.18^2 * 10 = 8.5 N
We have here what is known as parallel combination of resistors.
Using the relation:

And then we can turn take the inverse to get the effective resistance.
Where r is the magnitude of the resistance offered by each resistor.
In this case we have,
(every term has an mho in the end)

To ger effective resistance take the inverse:
we get,

The potential difference is of 9V.
So the current flowing using ohm's law,
V = IR
will be, 0.0139 Amperes.
the focal length <span> is much more decent for a concave, and also worse</span><span> for a convex mirror. When the image that is given, distance is good and decent, images are always on the same area of the mirror as the object given , and it is not fake. images distance is </span>never positive <span>, the image is on the oppisite side of the mirror, so the image must be virtual.</span>