5.4 Gravitational fields Flashcards
What is a gravitational field?
The rieogion around a body in which other bodies will feel a force due to the mass of the body
What are gravitaional field lines?
Lines that show the shape and the direction of the feild line at a point is the direction in which a mass mass would move when plced at that point.
What is gravitaional field strength?
AT any point in a gravitaional field is the force acting per unit mass at that point, g=F/m. Units are N kg-1.
Why do gravitaional fields occur?
Because ojects have mass. The more mass that body has, the morte that it will attract the smaller masses around it.
What sort of quantity is a gravitational field?
Vector quantity- it has size and direction.
What is a property of a gravitaional field?
They’re alway attractive.
What is the range of a gravitatioonal field?
Gravitational fields are infinite.
At twice the distance of a gravitaional field, what will the new strangth of the field be compared to the orginal? Why is this?
At twice the distance, the field has a quatre of the strength. This is an inverse square law.
e.g. 10 times the distannce will result in the feild strength decreaseing by 100th.
What is the eqauation for gravitational field strength?
Gravitational field strengt= force/ mass
What are the SI units for gravitatioanl field strength?
N kg-1
What is Newton’s law of gravitation?
- 2 bodies that have mass will attract another with a foce that is directly proportaional to the product of their masses and inversley proportional to the square of their separeation.
- F= -GMm/r^2
What does the graph look like showing the variation of the Earth’s gravitational feild strength outwards from the surface of the eatrth and then into thmosphere (mmodeeling the inverse square law)?
What is Kepler’s third law?
States that the square of the period of a planet orbiting the sun is proportioal to the mean radius of its orbit cubed: T^2 = r^3
What is a geostationary orbbit?
An orbit of the earth made by a satelite that has the same time period and orbital direction as the rotation of the earth, so appears to stay in the same spot in the sky.
What are Kepler’s laws of planetary motion?
- Planets travel around the sun in eliptical orbits.
- A line joining the sun to a planet will sweep out in equal areas in equal times.
- The time period of the orbit squared is proportional to the mean radius of the orit cubed.
What is Kepler’s second law?
A line joining the sun to a planet will sweep out equal areas in equal times.
