validate the law of universal gravitation (1 Viewer)

[xclusv2bhung]

how the hell do you do that ?
it was in our trials and i had no idea how to answer it
apparently , very few people got over 1 mark out of 3 in the trials.
i left it blank cos i had no idea.
bloody physics -.-

 

[Captain Gh3y]

a useful experiment may be to jump and discern whether or not one returns to earth.

 

[ssejamafone]

that's wierd.... i don't think it's in the syllabus, is it? well, i wouldn't be able to answer that question either. >_>" 0 marks for me. woo

 

[Captain Gh3y]

It could refer to the Cavendish experiment but that's certainly not in the Syllabus.

 

[Lucid Scintilla]

how the hell do you do that ?

Pardon? Oh, ref to title...

So anyway, if this is essentially asking for a pretty general proof, here:
Newton's First and Second Laws of Motion state, "blah, blah, blah" and "yadda, yadda, yadda", therefore a force must be acting on an object moving in a circle; the vector component of this acceleration is towards the centre of the circle, and this acceleration is centripetal acceleration. The force required to produce such an acceleration is defined by F_c = ma = mv²/r, where m is the mass of the object, v is the velocity, and r is the radius.

Then Law 2 plays its role; Newton calculated that:
F = m_sv²/|r_sBAO|, where:
m_s is the mass of the satellite;
v is the velocity at which it orbits;
r_sBAO is the distance between the satellite and a "BAO" ("Big Ass Object")

Newton, knowing Kepler's work, knew that the square of the orbital period for a satellite is proportional to the cube f its orbital radius.
V → (I can't find the "is proportional to" symbol) R/T
(der. from T = 2πr {two-pi-r, in case it doesn't show up properly; circumference} / v)

Putting these two equations (F = m_sv²/|r_sBAO and V → R/T) together, you may observe that V² → R^-1, and therefore the force the BAO (Bad Ass Object, e.g. Sun) exerts on a satellite is:
F = m_sv²/|r_sBAO| → R/T

Then Newton's Third Law of Motion states, "For every..."; this symmetry means that the two forces of gravitation depend on the masses of both objects in the same way, giving the form of the equation as:
F → m_sm_BAO/|r_sBAO|²

And then, Newton adds the constant which we know as capital G and gets rid of that (right now it's a wannabe) proportionality sign.
F = Gm_sm_BAO/|r_sBAO|²


Solved? Validated?

My bad if I make errors, heh.



Oh fucking shit, beaten to the punch... but with non-theory answers. It's waaay beyond high school Physics, 15-whatever the numbers are (edit: 15330). It's not in the syllabus. You better ask teachers for answers and explanations, xclusv2bhung.
Tell us about results, if any.

 

[wrxsti]

Newton was a good boy

 

[xiao1985]

maybe it's referring to the pendulum experiment. where you find out the gravitational constant using pendulum...

 

[xclusv2bhung]

@ Lucid_Scintilla :
LOL oh god , I`m sure it can`t have been THAT complicated ! they only gave us like 6 lines to write on or something ><"

@ Captain_gh3y :
LOL , love your replies dude.

& the rest of you posters .. thanks as well =)
I`ll post up the answer again when I find out what it is !
I`ll post it tomorrow !

 

[Forbidden.]

@ Lucid_Scintilla :
LOL oh god , I`m sure it can`t have been THAT complicated ! they only gave us like 6 lines to write on or something ><"

@ Captain_gh3y :
LOL , love your replies dude.

& the rest of you posters .. thanks as well =)
I`ll post up the answer again when I find out what it is !
I`ll post it tomorrow !

I've never heard of the use of absolute values in Physics, but only substitution, logarithms (to base 10), quadratic equations, Pythagoras but last but not least rather the most, substitution.

 

[Lucid Scintilla]

@ Lucid_Scintilla :
LOL oh god , I`m sure it can`t have been THAT complicated ! they only gave us like 6 lines to write on or something ><"

Not that it matters, it's without an underscore; but, as I said, not that it matters.

That's the theoretical proof. It is that complicated, unless you know an easier way; I want 'ocular proof'.

Surely you can write more than the number of given lines, right? I see it being done all the time by students at my school in 1/2 Yrlies and Yrlies, and they don't seem to get "marked down" or anything.

& the rest of you posters .. thanks as well =)
I`ll post up the answer again when I find out what it is !
I`ll post it tomorrow !

Cheers.

 

[xclusv2bhung]

Surely you can write more than the number of given lines, right? I see it being done all the time by students at my school in 1/2 Yrlies and Yrlies, and they don't seem to get "marked down" or anything.

Lol well there`s nothing wrong with writing over the amount of lines , but it`s kinda hard to squash in the entire proof when you dont get any extra paper and such.

& Yes sorry about your username.

I've never heard of the use of absolute values in Physics, but only substitution, logarithms (to base 10), quadratic equations, Pythagoras but last but not least rather the most, substitution.

Yeah , I think as bad as it got , we had logarithms in chem to work out pH.

 

[littlemaster]

I would basically crap on abot the pendulum, and prob. try to derive the formula from others......


can't wait for this answer!

 

[helper]

I would guess it is attempting for you to explain the scientific method to validate a law and is a rather generic question rather than specific.

IE.
A theory must be able to make predictions and they need to be able to checked experimentally. The experiments need to produce reliable results that validate the theory. There needs to multiple experiments to test the theory.

Outline a few experiments that you could use.
Pendulums
Cavendish
Moon orbiting Earth
Planets orbiting sun etc.

 

[Rohanesburg]

A proper validation would be to mathematically apply the inverese square law to the concept of the gravity field .

 

[jlnWind]

F= (Gm1m2)/R
I agree with what helper said, a good theory must be able to do two things
i) Be proven experimentally
ii) Make accurate predictions about phenomena

3 marks? 1- identify an experiment which validates this claim (i dont know of any... i think cavendish would be hard to come by esp. hsc phys)
a short google search came up with something from bookrags.com

Providing proof of the universality of Newton's law provided an impetus to eighteenth-century astronomers, including German-born English astronomer William Herschel (1738-1822). Although Herschel is most famous for his discovery of the planet Uranus in 1781, his celestial surveys not only provided an extensive star catalogue, they also provided abundant and unwavering validation of the universality of Newton's law.

but i still think that would be gay

2- make accurate predictions about phenomena- the fact that they were able to get to space without relativity but only the work of newton?
(maybe finding the orbital velocity, sub a few equations)
or... the fact that it predicts Kepler's Law of Thirds

 

[munchiecrunchie]

answer to this question:

1. the law of universal gravitation is consistent with the observations that all objects on earth fall to its centre, and that all planets orbit the sun in the solar system.
2. scientists in the past have been able to validate the law through experimentation
3. it has been used to predict the orbital paths of satellites, and predictions have been accurate.

im pretty sure this is the answer, since the teacher who told me this just so happened to have set the question in this test anyway.