Squares

General FreeBASIC programming questions.
dodicat
Posts: 6022
Joined: Jan 10, 2006 20:30
Location: Scotland

Re: Squares

Postby dodicat » May 12, 2018 8:48

Albert wrote :
With gravity? ,
How does rotation of a body affect its gravity, which is caused by mass alone..
...

Firstly, when a satellite is in orbit around the earth, gravity is considered to be a centripetal force.

But when a satellite is still on the earth's surface

Code: Select all



dim as double N  'normal force on satellite to be calculated.
dim as double g  'acceleration due gravity
dim as double v  'velocity of the earth's surface at the equator
dim as double r  'radius of earth
dim as double m  'apparent mass of a small satellite at a pole.
g=9.81             'm/s/s
v=460              'm/s
m=80               'kg
r= 6378e3          'm
N = m*g-m*(v^2/r)  'newtons (via centripetal force at equator).

print "Apparent mass of a small satellite at the North Pole  "; m
print "Apparent mass of a small satellite on the equator     ";N/g
sleep

 

I say apparent mass because there will also be a buoyancy factor, but it will be nearly the same at equator and pole.

We use the term gravity for various calculations, but we don't truly know what gravity is.
Which is why Albert is trying to get to the bottom of it all via a medium of ether.
albert
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Location: California, USA

Re: Squares

Postby albert » May 12, 2018 16:56

( moons speed mph = 2288 ) × (moons distance miles = 238,900) = 546,603,200 mph earth core speed
(Earth core speed mph = 546,603,200) ÷ ( Earth core circumference = 2,387 ) = 228,991 core circumferences per hour.
( core circumferences per hour = 228,991 ) ÷ 60 = 3,816 Earth Core RPM's...


If you orbit in the direction of the ether spinning in , you need to get up to ether speed for that orbit.

( core speed mph = 546,603,200 ÷ (( earth radius = ( 7,917.5 ÷ 2 ) + orbit miles up = 65) * 3.14159 ) = 43,240 mph speed needed to orbit at 65 miles up.
12.011276749 miles per second for 65 mile up orbit.

( core speed mph = 546,603,200 ÷ (( earth radius = ( 7,917.5 ÷ 2 ) + orbit miles up = 100) * 3.14159 ) = 42,867 mph speed needed to orbit at 100 miles up.
11.90769937 miles per second for 100 mile up orbit orbit.

( core speed mph = 546,603,200 ÷ (( earth radius = ( 7,917.5 ÷ 2 ) + orbit miles up = 1200) * 3.14159 ) = 33,727 mph speed needed to orbit at 1200 miles up.
9.368621239 miles per second for 1200 mile up orbit orbit. I think the 1200 mile up orbit , is actually 7.?? miles a second , 1 hour orbit.


Are the above calculation correct???? I might have messed up the circumference of the orbit..
deltarho[1859]
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Location: UK

Re: Squares

Postby deltarho[1859] » May 12, 2018 17:29

I haven't been following this thread fully but has anyone mentioned that an object in orbit is actually in free fall but is balanced by it's 'forward' motion wanting to 'pull away'. A 'push' will see the orbit increase.
caseih
Posts: 1392
Joined: Feb 26, 2007 5:32

Re: Squares

Postby caseih » May 12, 2018 19:06

albert wrote:Are the above calculation correct????
As they aren't based on real physics equations, no they are obviously not correct. Here's a neat little tool for calculating orbital velocities and periods for Earth orbit:
http://www.calctool.org/CALC/phys/astronomy/earth_orbit
albert
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Location: California, USA

Re: Squares

Postby albert » May 12, 2018 19:17

caseih wrote:
albert wrote:Are the above calculation correct????
As they aren't based on real physics equations, no they are obviously not correct. Here's a neat little tool for calculating orbital velocities and periods for Earth orbit:
http://www.calctool.org/CALC/phys/astronomy/earth_orbit


@caseih
I wanted to calculate the circumference of the orbits..Can you give me the formula?
Earth diameter = 7917.5 miles wide.

What would the circumference of the 65 mile up orbit be??
Richard
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Joined: Jan 15, 2007 20:44
Location: Australia

Re: Squares

Postby Richard » May 12, 2018 19:44

Earth diameter, D_earth = 7917.5 miles.
Height, h = 65 miles above the surface.
Orbit diameter, D_orbit = ( h + D_earth + h )
The circumference of the orbit will be C_orbit = Pi * D_orbit.
BasicCoder2
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Joined: Jan 01, 2009 7:03

Re: Squares

Postby BasicCoder2 » May 12, 2018 21:46

dodicat wrote:We use the term gravity for various calculations, but we don't truly know what gravity is.

We don't truly know what the ultimate Reality is. Scientists just make models to imitate things we observe or measure. Einstein's curved space/time just happens to be the best model of gravity we have at the moment for predicting and calculating how the planets behave. Any new model must at least behave according to all the behaviors what we have already observed and measured.
badidea
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Joined: May 24, 2007 22:10
Location: The Netherlands

Re: Squares

Postby badidea » May 12, 2018 21:56

BasicCoder2 wrote:Using the laws of physics as they are best described now you can run a simulation to see how well they predict the formation of Star/planet systems out of interstellar dust produced from the first generation stars.

Making such code is not easy as it involves a lot of (dust) particles and the process needs to be sped a lot to be useful. Also, I doubt we know how this interstellar dust 'looks like'. Also other forces like electrostatic and magnetic probably play a role. I'll wait for Albert to solve the mysteries of the universe...

edit: Hey, you changed your post :-)
BasicCoder2
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Joined: Jan 01, 2009 7:03

Re: Squares

Postby BasicCoder2 » May 12, 2018 22:09

.
Last edited by BasicCoder2 on May 14, 2018 22:25, edited 1 time in total.
BasicCoder2
Posts: 3404
Joined: Jan 01, 2009 7:03

Re: Squares

Postby BasicCoder2 » May 12, 2018 22:19

.
Last edited by BasicCoder2 on May 14, 2018 22:25, edited 1 time in total.
Richard
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Joined: Jan 15, 2007 20:44
Location: Australia

Re: Squares

Postby Richard » May 12, 2018 23:13

badidea wrote:Making such code is not easy as it involves a lot of (dust) particles and the process needs to be sped a lot to be useful. Also, I doubt we know how this interstellar dust 'looks like'.

We know what the dust looks like because radio and optical astronomy measures the absorption and scattering of radiation from background stars by that dust. The knowledge of space chemistry has advanced as improved density plots of molecular MASER radiation from galaxy forming regions are now being imaged. That is because wideband cryogenic microwave receivers with faster hardware FFT spectrum analysers have been developed.

The formation of galaxies from dust clouds has been computed over the last 25 years on a series of parallel pipelined super-computers. They are called the “GRAPE Project”, originally based in Tokyo and managed by Junichiro Makino. GRAPE 4 and 6 held world records for supercomputers. This will give you some idea of the history.
https://en.wikipedia.org/wiki/Gravity_Pipe

Junichiro Makino moved to the IAS in Princeton, New Jersey. Tutorials and software for the GRAPE project is freeware and available … Start here; https://www.ids.ias.edu/~piet/act/comp
These galaxy formation models are, as far as I could see, very accurate and realistic. Integration is the weakest link in any physical n-body simulation. Makino et al have taken a lot of trouble to get the integration correct and developed advanced ways of managing the evolving barycentre trees that have accelerated the simulation.

GRAPE 6 processors are available on the market today, so they are also being used for things like molecular chemistry. I am waiting to find out the tricks used for GRAPE 7, so I can replace my GPU. I would expect it to be a technology advance in processor throughput by a factor of 4, with a power reduction by a factor of maybe 3.
albert
Posts: 5311
Joined: Sep 28, 2006 2:41
Location: California, USA

Re: Squares

Postby albert » May 13, 2018 0:54

For gravity dropping off 1 mph per mile distance.

(For 65 mile high orbit)
( moons speed mph = 2288 ) × (moons distance miles = 238,900) = 546,603,200 mph earth core speed
546,603,200 ÷ orbit height miles = 65 = 8,409,280 ÷ 3600 = 2335.91 miles a second orbit speed
25,077 miles orbit circumference ÷ 2335.91 = 10.73 seconds per orbit.

(For 100 mile high orbit)
( moons speed mph = 2288 ) × (moons distance miles = 238,900) = 546,603,200 mph earth core speed
546,603,200 ÷ orbit height miles = 100 = 5,466,032 ÷ 3600 = 1518.34 miles a second orbit speed
25,187 miles orbit circumference ÷ 1518.34 = 16.58 seconds per orbit.

(For 1,200 mile high orbit)
( moons speed mph = 2288 ) × (moons distance miles = 238,900) = 546,603,200 mph earth core speed
546,603,200 ÷ orbit height miles = 1200 = 455,502.66 ÷ 3600 = 126.52 miles a second orbit speed
28,643 miles orbit circumference ÷ 126.52 = 226.39 seconds per orbit.

(For 2,000 mile high orbit)
( moons speed mph = 2288 ) × (moons distance miles = 238,900) = 546,603,200 mph earth core speed
546,603,200 ÷ orbit height miles = 2000 = 273,301.6 ÷ 3600 = 75.917 miles a second orbit speed
31,156 miles orbit circumference ÷ 75.917 = 410.405 seconds per orbit.

(For 238,900 mile high orbit) ( moon orbit)
( moons speed mph = 2288 ) × (moons distance miles = 238,900) = 546,603,200 mph earth core speed
546,603,200 ÷ orbit height miles = 238,900 = 2,288 ÷ 3600 = 0.635555556 miles a second orbit speed
776,463.17 miles orbit circumference ÷ 0.635555556 = 1,221,707.78 seconds per orbit.

???__I'm not sure my formulas are correct__???
( It should be , minutes per orbit )
Last edited by albert on May 13, 2018 1:34, edited 1 time in total.
caseih
Posts: 1392
Joined: Feb 26, 2007 5:32

Re: Squares

Postby caseih » May 13, 2018 1:17

Albert did you look at that web site I linked to? It calculates the average orbital speed at various heights accurately. As your figures differ wildly from the real numbers, then you can be sure your formulas are not correct.

BTW I've been watching the PBS Space Time youtube channel lately. I only understand 25% of what he talks about, but it's quite interesting.
dodicat
Posts: 6022
Joined: Jan 10, 2006 20:30
Location: Scotland

Re: Squares

Postby dodicat » May 14, 2018 15:24

Hi Albert.
If you enter the height in meters, the orbital speed and period are shown.

Code: Select all

 



const M= 5.972e24    ' mass ofearth
const G= 6.67408e-11 'gravitational constant
const pi=4*atn(1)

sub orbit(height as double,byref speed as double,byref period as double)
    height+=6378000          'radius of earth added
    speed= sqr(G*M/height)
    dim as double circumference=2*pi*height
    period=circumference/speed
end sub


dim as double sp,pe,height
height=678000
orbit(height,sp,pe)
print "Height above Earth (metres) = ";height
print "orbital speed (km/second)   = ";sp/1000
print "orbital period (hours)      = ";pe/60/60
sleep

 
lizard
Posts: 440
Joined: Oct 17, 2017 11:35
Location: Germany

Re: Squares

Postby lizard » May 14, 2018 19:04

Dodicat, you like astronomical calculations? I have a interesting lib for you.

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