Gravitational Fields 🛰️

Question 1

Explain the feeling of ‘weightlessness’ of passengers in an aeroplane

Answer 1

• passengers experience no normal contact force
• acceleration of passengers is the same as acceleration of the aeroplane

Question 2

What is a gravitational field?

Answer 2

A region in which objects with mass experience an attractive force

Question 3

State Newton’s law of gravitation

Answer 3

The force between two point masses is directly proportional to the product of their masses and inversely proportional to the square of their separation

Question 4

State Kepler’s first law

Answer 4

The orbit of a planet is an ellipse with the sun at one of two foci

Question 5

State Kepler’s second law

Answer 5

A line segment joining a planet and the sun sweeps out equal areas in equal time intervals

Question 6

State Kepler’s third law

Answer 6

The square of the orbital period is directly proportional to the cube of its average distance from the sun

Question 7

What is a polar orbit?

Answer 7

• An orbital path that circles the poles
• Provides a complete view of the earth as it rotates

Question 8

What is a geostationary satellite?

Answer 8

A satellite with an orbital period of 24 hours -> this means it is always above the same point on the earth

Question 9

List 3 features of a geostationary orbit

Answer 9

• Orbit above the earth’s equator
• Rotate in the same direction the earth rotates
• Have an orbital period of 24 hours

Question 10

Define gravitational potential

Answer 10

Work done per unit mass to bring that mass from infinity to a point in the gravitational field

Question 11

Define gravitational potential energy

Answer 11

Work done to bring a mass from infinity to a point in a gravitational field