newton invented gravity

Question 1

what is a gravitational field?

Answer 1

-a region of space in which any mass will experience a force of attraction. all masses have a gravitational field around them.

Question 2

what are gravitational field lines?

Answer 2

-lines of force used to map the gravitational field pattern around an object.

Question 3

what do the field lines look if the field is uniform?

Answer 3

-field lines will be parallel and equidistant

Question 4

what is newtons gravitational law in words?

Answer 4

-force is proportional to the product of the masses and inversely proportional to the square of their seperation.

Question 5

explain what gravitational field strength in a radial field would be? (whats it proportional to etc)

Answer 5

• its directly proportional to the mass of the object creating the gravitational field.
• inversely proportional to the square of the distance from the centre of mass of the object.

Question 6

state kepler first law? explain brief?

Answer 6

• the orbit of a planet is an ellipse with the Sun at one focus.
• since in most cases orbits have low eccentricity their orbits can be modeled as circles.

Question 7

state kepler second law? explain why?

Answer 7

• a line segment joining a plane and the sun sweeps out equal areas during equal intervals of time.
• this is because speed of the planet is not constant

Question 8

kepler third law?

Answer 8

-the square of the orbital period T of a planet is directly proportional to the cube of its average distance r from the sun. (for all planets). this can be proved by considering the forces acting on the object. centripetal force is required to keep the planet in orbit and this force is provided by the gravitational force of the sunuse

Question 9

uses of satellites?

Answer 9

• communications ,tv
• military use: reconnaissance
• scientific research
• weather and climate
• gps

Question 10

what are geostationary satellites?

Answer 10

• a geostationary satellites is placed in a specific orbit so that it remains above that point of the earth whilst the earth rotates.

Question 11

conditions in order to be a geostationary satellites/

Answer 11

• be in orbit above the earth’s equator
• rotate in the same directions as the earth’s rotation
• have an orbital period of 24 hours

Question 12

what is the gravitational potential?

Answer 12

-the gravitational potential at a point is the gravitational potential energy per unit mass at that point

Question 13

what does the gravitational potential in a radial field depend on?

Answer 13

• the distance r from the point mass producing the gravitational field to that point.
• the mass of the point mass