Flashcards
Gravitational fields
Cards in this deck (43)
- 1define gravitational fielda field created around any object with mass, extending all the way to infinity, but diminishing as the distance from the centre of mass of the object increases
- 2define gravitational field strengththe gravitational force exerted per unit mass at a point within a gravitational field
- 3define gravitational field lineslines of force used to map the gravitational field pattern around any object having mass
- 4define radial fielda symmetrical field that diminishes with distance^2 from its centre, such as the gravitational field around a spherical mass or the electrical field around a spherical charged object
- 5define point massa mass with negligible volume
- 6define uniform gravitational fielda gravitational field in which the field lines are parallel and the value for g stays constant
- 7define newton's law of gravitationthe force between two point masses is directly proportional to the product of the masses and inversely proportional to the square of the separation between them
F = G(Mm)/R^2 - 8define gravitational constantthe constant in newton's law of gravitation F = G(Mm)/R^2
with a value of 6.67x10^-11 - 9define kepler's first lawthe orbit of a planet is an ellipse with the sun at one of the two foci
- 10define kepler's second lawa line segment connecting a planet to the sun sweeps out equal areas during equal intervals of time
- 11define kepler's third lawthe square of the orbital period T of a planet is directly proportional to the cube of its average distance r from the sun
- 12define ellipsean elongated circle with two foci
- 13define eccentricitya measure of the elongation of an ellipse
- 14define aphelionthe furthest point from the sun in an orbit
- 15define perihelionthe closest point to the sun in an orbit
- 16define astronomical unitthe mean distance from the earth to the sun
- 17define geostationary satellitesa satellite that remains in the same position relative to a spot on the Earth's surface, by orbiting in the direction of the earth's rotation over the equator with a period of 24 hours
- 18define gravitational potentialthe work done per unit mass to bring an object from infinity to a point in the gravitational field
- 19give the equation for gravitational field strengthg = f/m
- 20give the equation for newton's law pf gravitationF = G(Mm)/R^2
where F is the force between two point masses, G is 6.67x10^-11, M is the mass of the object orbited, m is the mass of the object orbiting, and R is the distance between them - 21what is F directly proportional to1/R^2
Mm - 22what does the graph of F against r look like
- 23what does the graph of F against 1/r^2 look like
- 24how do you derive the equation for gravitational field strength in a radial field?
- 25what does the negative sign in the equation for gravitational field strength represent?it shows that the gravitational field strength is in the opposite direction to the displacement from the centre of mass
- 26what is the gravitational field strength directly proportional toM
1/r^2 - 27why are most planets orbits modelled as circles?they have low eccentricity
- 28how can kepler's third law be written as an equationT^2 / r^3 = constant
- 29how does centripetal force relate to gravitational forcecentripetal force on planet = gravitational force on planet
mv^2 / r = GMm/r^2
or
v^2 = GM / r - 30how can you find the speed of a planetv = 2pi r / T
- 31what is the equation for T^2T^2 = (4pi^2/GM)r^3
- 32define satellitea body orbiting around a planet
- 33what is the equation for gravitational force of a satelliteF = mv^2/r = GMm/r^2
- 34what is the equation for speed of a satellitev = square root (GM/r)
- 35name uses of geostationary satellites and advantages and disadvantagesTV and phone signals, local weather satellites. lower resolution, expensive, risk of them falling back to earth, likely to break or malfunction
- 36name uses of polar satellites a advantages and disadvantagndesGPS systems, military spying, space research since they have lower orbit so higher resolution, cannot continuously communicate with a spot on earth's surface
- 37what are polar orbitsorbits which circle the poles
- 38what is low earth orbitorbits which are close to the earth,
- 39what is symbol for gravitational potential and example valueVg, all values are negative because it is 0 at infinity, all are negative because gravitational force is attractive
- 40what are the factors which decide the gravitational potential in a radial fielddistance from the point mass producing the gravitational field to that point, the mass of the point mass
- 41what is the equation for gravitational potentialVg = -GM/r
- 42what is the equation for gravitational potential energyE = m(Vg) = - GMm/r
- 43what is the equation for escape velocityv = square root (2GM/r)
Information
- Description
- physics A level (M5 Chapter 18 Gravitational fields ) Flashcards on Gravitational fields , created by lizabeth rawson on 03/12/2021.
- Created by
- lizabeth rawson
- Views
- 0
- Rating