Chapter 18 - Gravitational Fields Flashcards
What creates a gravitational field?
Any object with mass
How far does a gravitational field stretch?
To infinity
What is gravitational field strength?
The force experienced per unit mass in a gravitational field
What do the gravitational field lines on a radial gravitational field diagram show?
The field is attractive
The shape of the field
The fields is centred around a single point mass
The closer the lines are together the stronger the field is a that point
How can the Earth’s gravitational field be modelled when close to the surface?
As a uniform gravitational field.
What is Newton’s law of gravitation?
The force between two point masses is:
directly proportional to the product of the masses
inversely proportional to the square of their separation
Why is every gravitational force negative?
To show that it is an attractive force.
What is Kepler’s first law of planetary motion?
The orbit of a planet is an ellipse with the Sun as one of the two foci.
What is Kepler’s second law of planetary motion?
A line segment joining a planet and the Sun sweeps out equal areas during equal time periods.
What is Kepler’s third law of planetary motion?
The square of the orbital time period of a planet is directly proportional to the cube of its average distance from the Sun.
State 4 uses of satellites
Communications
Reconnaissance
Scientific research
Weather forecasting
State the three properties of a geostationary orbit
Orbit above the equator
Rotate in the same direction as the Earth
Orbital time period of 24 hours
What is gravitational potential?
The work done per unit mass to move an object to that point from infinity.
What is the gravitational potential of any object at infinty?
0
What is the area under a gravitational force against distance graph?
Gravitational potential energy
