Dot point help (1 Viewer)

[Fermentation]

what needs to be addressed under this syllabus dot point?

Discuss the importance of Newtons Law of Universal Gravitation in the understanding and calculating the motion of satellite

 

[xiao1985]

errr gravity = centripetal force?! so you get the whole kepler's 3rd law coming ( i think)

 

[twilight1412]

wellid say you'd need to break down the entire equation and evaluate it

action at a distance point of view

ie F = GMm
R²

where M is the mass of the Earth
and m is mass of the satellite

F gives the force experienced by the object of mass m at a distance R from the center of the earth

g = GM
R²

this allows you to look at the gravitional field strength or acceleration towards the earth a certain displacement from the earth irrespective of its mass

you should also probably note somewhere that the earth's gravitational field strength is subject to the inverse square law

 

[ann.shack]

Newton's Universal Law of Gravitation can allow scientists who the mass of the Earth and their sateliltes to calculate what height they will need to be put into orbit to undergo unifrom circular motion.
Force of gravity G(m1*m2/d squared)
G - fixed
mass 1 - fixed
mass 2 - fixed
d squared - variable.
therefore, the distance is the the only thing that depends on the satelite to reach the right velocity in order to orbit the planet.
hope that helps (first half taken from matt's dot point syllabus, 2005)

 

[ianc]

yeah, all those things are good to write, but i think the essence of the point is what xiao1985 said: equating gravitational force with centripetal force

as you know, this formula is (R³/T²) = (GM / 4pi²)

or in other words: variable/variable = constant

So it demonstrates that there is a relationship between the radius of the orbit and the period of an orbit of a satellite which is very useful - eg it allows you to work out exactly how high you need to position a geostationary satellite - and also a whole host of other things.

Also shows that the mass of the satellite is irrelevant - it will always orbit with the same radius and period.

Hope this made sense!