10. Gravitational Astrophysics

Question 1

Keplers 1st law

Answer 1

The orbit of every planet is an ellipse with the sun at a focus

Question 2

Keplers second law

Answer 2

For any planet, the radius vector sweeps out equal areas in equal times

Question 3

Keplers third law

Answer 3

The cubes of the semi-major axis of the planetary orbits are proportional to the squares of the planetary periods

Question 4

Define gravitational potential energy

Answer 4

The work required to separate two bodies to an infinite distance from the initial separation

Question 5

Gravitational theorem 1

Answer 5

A body inside a spherical shell of matter experiences no net gravitational force from that shell

Question 6

Gravitational theorem 2

Answer 6

The gravitational force on a body that lies outside a closed spherical shell of matter is the same as it would be if all the shells matter were concentrated into a point at its centre