Answer:
Well, I think you're talking about kinematics, especially uniform rectilinear motion. We know that there is a specific equation for that:
S = Vt + S0
With S being the distance, V the velocity, t the time and S0 the initial distance (initial displacement).
From this you can calculate t, if that's what you want.
Answer:
It is an example of negative feedback mechanism
Explanation:
Negative feedback mechanism is the process by which the output of a system, process or mechanism is fed back into the input in order to reduce the error in the system.
In the system described in this question, the reabsorption of water is the output, a feedback signal is sent to the control center, which is the input in order to control the release of the hormone responsible for reabsorption of water into the blood.

The equivalent gravitational force is ~

We know that ~

where,
= mass of 1st object = 500 kg
= mass of 2nd object = 20kg
- G = gravitational constant =

- r = distance between the objects = 2.12 m
Let's calculate the force ~
The farther apart the two objects, the weaker the gravitational attraction between them.