Gravitational Fields

Question 1

What is a gravitational field?

Answer 1

The area around a mass where any other mass will experience a force.

Question 2

What is gravitational field strength?

Answer 2

The force per unit mass on a 1kg mass placed at that point in the field

Question 3

What is gravitational potential?

Answer 3

The work done in moving a unit mass (1kg) from infinity to that point, r.

Question 4

What is work done (change in GPE) to move an object from potential V1 to V2?

Answer 4

Change in Work done = mass * change in potential.
1/2*mv^2 = mass * change in potential.

Question 5

What is Kepler’s 1st Law?

Answer 5

Planets travel around the sun in elliptical orbits with the sun as one of the two foci.

Question 6

What is Kepler’s 2nd Law?

Answer 6

A line joining the Sun to a planet will sweep out equal areas in equal times.

Question 7

What is Kepler’s 3rd Law?

Answer 7

The T^2 to r^3 since 4pi^2/GM is constant.

Question 8

How to find proof of Kepler’s 3rd Law?

Answer 8

F = GMm/r^2
F = mw^2r
Make them equal.

Question 9

How to find the time period for a given radius?

Answer 9

w = 2pi/T
F = mr*w^2
F = GMm/r^2
input values and rearrange for T^2

Question 10

How to find speed v for a given radius?

Answer 10

F= mv^2
F = GMm/r^2
Make equal and rearrange for v

Question 11

How does microwave background radiation support the cosmological principle?

Answer 11

It is isotropic