Answer:
Explanation below:
Explanation:
Annual motion describes the changes in motion of the earth around the sun. Diurnal motion can be better understood as the change in motion caused by Earths rotation at the poles.
This might not be the answer you were looking for, your question is very vague.
It would be B, like charges repel and unlike charges attract.
Answer:
Period of the signal.
Explanation:
So, this question is all about a concept in physics or astronomy which is called or known as Radiation Astronomy and Galactic Nuclei that are active. This concept talks most about Quasars; a powerful radiating object which derives its power from black holes.
When You take a look at Quasars, we get the to know that the more you think you can see, the more they move away from us.
Thus, when "You are observing the radiation from a distant active galaxy and you notice that the amplitude of the signal varies in strength regularly over a certain period. The maximum possible size for the source of this radiation can now be calculated from the "PERIOD OF THE SIGNAL.
NB: not the amplitude but the period.
B. only its velocity should change
Answer:
The gravitational force is related to the mass of each object.
The gravitational force is an attractive force.
Explanation:
Gravitational force is a long range force of attraction between any two masses.
Mathematically given as :

where:
are the masses
r= distance between the center of mass of the two objects.
G= gravitational constant = 
From the above relation of eq. (1) it is clear that,
Gravitational force is inversely proportional to the square of the distance and directly proportional to the masses.
The mass of an object is independent of its size due to the fact that density may vary for different objects.
The force of gravity varies with height as:

where:

gravity at height
of the center of mass of the object from the center of mass of the earth.
and we know that force:

where: m= mass of the object.