07 Gravitational Field

Question 1

The meaning of the term “gravitational field”

Answer 1

A gravitational field is a region of space in which a mass experiences a force due to the presence of another mass.

Question 2

Conditions for geostationary orbit

Answer 2

An object in a geostationary orbit appears at a fixed position in the sky with respect to ground observers on the surface of the rotating Earth. For this to happen, the object must (i) be directly above the Earth’s equator. (ii) have a orbital period equal to the Earth’s rotational period (24 hrs). (iii) be orbiting from West to East.

Question 3

Definition of gravitational potential energy

Answer 3

The gravitational potential energy of a mass at a point in a field is defined as the work done by an external agent in bringing that mass from infinity to that point.

Question 4

Definition of gravitational potential

Answer 4

The gravitational potential at a point in a field is defined as the work done per unit mass by an external agent in bringing a test mass from infinity to that point.

Question 5

Formula for gravitational force

Answer 5

Question 6

Formula for gravitational field strength

Answer 6

Question 7

Formula for gravitational potential energy

Answer 7

Question 8

Formula for gravitational potential

Answer 8

Question 9

Derivation for Kepler’s Third Law

Answer 9