# Question about gravitational acceleration

1. Oct 26, 2012

### Crazymechanic

not so good at math so please help me.When I play with those artificial gravity or should say centripetal force calculators I get some pretty big numbers so I need some verification of them.
Is it true that spinning a let's say 1m. radius disc with 50 000rpm/min you would get like 2795609.8954 g force on the side of the disc? And if so isn't that close or even over to that you normally would get on a middle sized star? Certainly bigger than our sun.?

How could I calculate the highest possible g force a specific flywheel or material or disc could withstand?

And the last thing a disc or whatever solid material rotating fast doesn't get very hot , well if we don't consider the air resistance and friction, but now let's imagine that around the disc is a chamber full with gas and we spin the disc very fast does the gas act similar as the solid or does the gas heat up differently?

2. Oct 26, 2012

### Naty1

F = ma..right?? and for a rotating object ....a = v2/r

the v is the tangential velocity so you'll have to convert 50,000 RPM to a velocity. Each revolution travels a distance of 1 circumference or C = 2[pi]r....and you'll have 50,000 of these each minute....

not likely practical to calculate it.....use an experimentally determined figure:

see

http://en.wikipedia.org/wiki/Tensile_strength

3. Oct 26, 2012

### jbriggs444

If you look at

http://en.wikipedia.org/wiki/Flywheel_energy_storage

you can get some additional insights.

One observation is that the maximum energy density you can get is proportional to σ/ρ where σ is the tensile strength of the material and ρ is its density.

This means the the maximum tangential velocity is proportional to the square root of σ/ρ
And that means that the maximum rotation rate is roughly given by sqrt(σ/ρ)/r.

4. Oct 26, 2012

### Crazymechanic

Thanks for the answers , oh by the way can somebody answer the last part of my thread?

And the last thing a disc or whatever solid material rotating fast doesn't get very hot , well if we don't consider the air resistance and friction, but now let's imagine that around the disc is a chamber full with gas and we spin the disc very fast does the gas act similar as the solid or does the gas heat up differently?

5. Oct 26, 2012

### Crazymechanic

So F=ma mass let's say 5 tons and radius of the disc 10 meters. and "a" is like (assuming 50 000rpm) C = 2[pi]r that would be like 2x(3.14x10) == 2x 31.4=62.8
now a = v2/r that would mean a=62.8x62.8/10 is equal to 394.384

now the F=ma part. F=5000x 394.384= 19711920 (N)

I'm sorry for my abstract nonsense type of calculus but could someone verify that I did the calculations right?
And 19711920 N , how do I convert that to G ?

Thanks.

6. Oct 28, 2012

### Crazymechanic

Anyone? And yes could someone tell me about how does gas or plasma states react to tangential pressure compared with a solid material?