Spin Doctor

12-25-2010, 09:21 AM

Physics was a long time ago. Need the equation for the force in gees on a rotating object. As in say the classic wheel shaped space station.

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Spin Doctor

12-25-2010, 09:21 AM

Physics was a long time ago. Need the equation for the force in gees on a rotating object. As in say the classic wheel shaped space station.

Lew Hartswick

12-25-2010, 10:12 AM

I have the text books from my physics classes on the shelf and will

look it up but it's something like mass times angular acceleration

all in the right units. :-)

Back to you in a bit.

...lew...

look it up but it's something like mass times angular acceleration

all in the right units. :-)

Back to you in a bit.

...lew...

philbur

12-25-2010, 10:49 AM

This one is about as simple as it gets:

http://aquaticpath.umd.edu/nomogram.html

Phil

Physics was a long time ago. Need the equation for the force in gees on a rotating object. As in say the classic wheel shaped space station.

http://aquaticpath.umd.edu/nomogram.html

Phil

Physics was a long time ago. Need the equation for the force in gees on a rotating object. As in say the classic wheel shaped space station.

mbensema

12-25-2010, 10:52 AM

The basic formula is: w^2 x R / gravity constant

w = radians per second

R= radius in meters or feet

gravity constant is 9.81 m/sec^2 for metric and 32.2 in Imperial

Using rpm, the formula is: (rpm x 2 x 3.1415 / 60)^2 x R / gravity constant

w = radians per second

R= radius in meters or feet

gravity constant is 9.81 m/sec^2 for metric and 32.2 in Imperial

Using rpm, the formula is: (rpm x 2 x 3.1415 / 60)^2 x R / gravity constant

Evan

12-25-2010, 10:59 AM

That was the very first mainframe program I wrote in '67.

Relative Centrifugal Force= 0.00001118*radius in cm*rpm^2

or

RCF=0.0000283972*radius in inches*rpm^2

Relative Centrifugal Force= 0.00001118*radius in cm*rpm^2

or

RCF=0.0000283972*radius in inches*rpm^2

Lew Hartswick

12-25-2010, 11:00 AM

OK. University Physics, Mechanics Heat and Sound by Sears and Zemansky. Chapter 6 , section 2 circular motion, and section 3, Centripetal force:

It boils down to the velocity around the circle is: v = 2 pi R / T

After a bunch of derivitives.

the radial acceleration is: a = v squared / R

Now everyone know force is mass time acceleration so :

The radial force is the mass times the "speed" of the object going around the circle squared divided by the radius of rotation.

The units of Force will be dependant on the units of mass and linear measure.

Mass in grams and dimensions in cm = force in dynes.

Remember that G's are not a unit of Force

How much deeper do you want to go?

...lew...

on edit I see it was a waste of time

It boils down to the velocity around the circle is: v = 2 pi R / T

After a bunch of derivitives.

the radial acceleration is: a = v squared / R

Now everyone know force is mass time acceleration so :

The radial force is the mass times the "speed" of the object going around the circle squared divided by the radius of rotation.

The units of Force will be dependant on the units of mass and linear measure.

Mass in grams and dimensions in cm = force in dynes.

Remember that G's are not a unit of Force

How much deeper do you want to go?

...lew...

on edit I see it was a waste of time

3jaw

12-25-2010, 02:09 PM

F=mrω²

Where:

F=Force

m=mass

r=distance of mass from center of rotation

ω=rotational velocity in radians/second

Where:

F=Force

m=mass

r=distance of mass from center of rotation

ω=rotational velocity in radians/second

Black_Moons

12-25-2010, 03:22 PM

Weird, I never would of guessed its exponential with speed. I would of thought it would be linear.

John Stevenson

12-25-2010, 03:34 PM

Whirlybits x Speed divided by chucky off bits.

beanbag

12-25-2010, 06:20 PM

Weird, I never would of guessed its exponential with speed. I would of thought it would be linear.

It's quadratic, not exponential.

It's quadratic, not exponential.

oldtiffie

12-25-2010, 07:14 PM

F=mrω²

Where:

F=Force

m=mass

r=distance of mass from center of rotation

ω=rotational velocity in radians/second

Yup.

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

Where:

F=Force

m=mass

r=distance of mass from center of rotation

ω=rotational velocity in radians/second

Yup.

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

Void

12-25-2010, 08:16 PM

If you ever get stuck on a basic, or even not-so-basic, concept in Physics go to the HyperPhysics (http://hyperphysics.phy-astr.gsu.edu/Hbase/hframe.html) website at Georgia State University. It has a very easy to navigate visual tree of concepts or you can just use the index. It even has built in calculators and graphers for most of the formulas.

Bookmark it.

-DU-

Bookmark it.

-DU-

Evan

12-25-2010, 08:28 PM

That is one of the better ones that I use regularly. Another is Eric Weisstein's Wolfram Mathworld (http://mathworld.wolfram.com/). If you need the formula for anything mathematical it is there.