(a) Force between the two charges
The electrostatic force between the two charges is given by:

where k is the Coulomb's constant, q1 and q2 the two charges, r their separation.
In this problem:



Substituting into the equation, we find

(b) direction of particle q2
Particle q2 wants to move in the direction of the force acting on it. The direction of the force depends on the relative sign of the two charges: like charges attract each other, opposite charges repel each other. In this case, the two charges are both positive, so they repel each other and q2 tends to move away from particle q1.
Inertia
<span> An object at rest stays at rest and an object in
motion stays in motion with the same speed and in the same direction
unless acted upon by an unbalanced force.this tendency to retain its motion is referred to as Inertia </span>
An example would be gravity
A) The biggest astronomical object is the Universe, which contains billions of galaxies among which there is the Milky Way.
The Milky Way contains thousands of planetary systems, among which the Solar System.
The Solar System contains many <span>planets <span>(but only one star, the Sun)</span>,</span> among which there is Earth.
Therefore you can label:
A = Universe, B = Milky Way, C = Solar system, D = Earth
b) Given what we said before, you could label D also any other planet in the Solar System, therefore you can choose among Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and Neptune.