(b) Always act on the different bodies in opposite directions
The electrostatic force between the two ions is 
Explanation:
The electrostatic force between two charged particle is given by Coulomb's law:

where
is the Coulomb's constant
are the two charges
r is the separation between the two charges
In this problem, the ion of sodium has a charge of

while the ion of chlorine has a charge of

And the distance between the two ions is

Substituting, we find the electrostatic force between the two ions:

where the negative sign simply means that the force is attractive, since the two ions have opposite charge.
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Answer:
The value is 
Explanation:
From the question we are told that
The velocity which the rover is suppose to land with is
The mass of the rover and the parachute is
The drag coefficient is
The atmospheric density of Earth is 
The acceleration due to gravity in Mars is 
Generally the Mars atmosphere density is mathematically represented as

=> 
=> 
Generally the drag force on the rover and the parachute is mathematically represented as

=>
=>
Gnerally this drag force is mathematically represented as

Here A is the frontal area
So

=> 
=> 
When talking about orbits, it would have to be a mixture of both A. and B. since Newton's first law, gravity plays a huge part in an orbit. However, the universal gravitation law also tells us the relationship between two massive objects in orbit. But to choose only one, it would have to be B. Newton's first law
Answer: A force must cause a displacement in order for work to be done. A book falls off a table and free falls to the ground. Yes. This is an example of work.
Explanation: