Halo: Combat Evolved

imported_Rat

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Sep 11, 2006
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In the video game Halo, there's a spinning, ring-shaped space station which uses centrifugal force to simulate gravity. The halo is spinning relative to what? Shouldn't it spontaneously decelerate?
Let's say you have two concentric halos spinning in opposite directions. Are they both spinning or is one standing still?
 

Xyo II

Platinum Member
Oct 12, 2005
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Originally posted by: Rat
In the video game Halo, there's a spinning, ring-shaped space station spins which uses centrifugal force to simulate gravity (washing machine spin cycle). The halo is spinning relative to what? Shouldn't it spontaneously decelerate?
Let's say you have two concentric halos spinning in opposite directions. Are they both spinning or is one standing still?

The space station that you are talking about is halo itself. And in the game, it uses centrifugal force and an artificial gravity generator. As to the two concentric halos spinning in opposite directions, it depends on your point of view. (I'm assuming these rings are not connected) Relative time frames come in mind, but you can think of it as if you were on a train moving 60 mph, and are walking along the isle, are you walking 62 mph (train's speed + walking speed in the train) or 2 mph (your walking speed)? If it is a translucent train, someone on the outside would see that you are walking 62 mph, but you would see yourself as walking 2 mph- it's a matter of perspective. As for your questions on what the ring is spinning relative to, maybe you just need a review of centrifugal force. The ring shouldn't spontaneously decelerate, seeing as there is little force keeping the ring from spinning forever.

edit: mistype
 

Xyo II

Platinum Member
Oct 12, 2005
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The sun is (relatively) standing still and it "generates" gravity.. but the main force acting as gravity is centrifugal force, from the spinning of the ring. The "artificial gravity generators" are science fiction here.
 

msparish

Senior member
Aug 27, 2003
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Conservation of angular momentum will keep the ring rotating. For example, think of the earth...it keeps rotating. Another example is to think of a bike wheel. If you spin the wheel it continues to spin. What eventually stops it is the friction (from the bearings, air, etc.) not because it is spontaneously slowing down.
 

blackllotus

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May 30, 2005
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Originally posted by: Rat
Let's say you have two concentric halos spinning in opposite directions. Are they both spinning or is one standing still?

As already stated, it depends on your frame of reference. However, regardless of the frame of reference, objects on either spinning halo will experience forces from the constant acceleration.
 

imported_Rat

Senior member
Sep 11, 2006
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Originally posted by: blackllotus
Originally posted by: Rat
Let's say you have two concentric halos spinning in opposite directions. Are they both spinning or is one standing still?

As already stated, it depends on your frame of reference. However, regardless of the frame of reference, objects on either spinning halo will experience forces from the constant acceleration.

Is it possible for them to stop generating CF and reach equilibrium, yet still spin along their own axis?
 

TuxDave

Lifer
Oct 8, 2002
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Originally posted by: Rat
Originally posted by: blackllotus
Originally posted by: Rat
Let's say you have two concentric halos spinning in opposite directions. Are they both spinning or is one standing still?

As already stated, it depends on your frame of reference. However, regardless of the frame of reference, objects on either spinning halo will experience forces from the constant acceleration.

Is it possible for them to stop generating CF and reach equilibrium, yet still spin along their own axis?

If a point on the halo is moving in a circular path, it's essentially accelerating towards the center of the circle and perpendicular to it's current path. To accelerate that object it requires a centripetal force. So no, as far as I can tell, you cannot have a circular moving path without being subject to force.
 

imported_Rat

Senior member
Sep 11, 2006
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Originally posted by: TuxDave
Originally posted by: Rat
Originally posted by: blackllotus
Originally posted by: Rat
Let's say you have two concentric halos spinning in opposite directions. Are they both spinning or is one standing still?

As already stated, it depends on your frame of reference. However, regardless of the frame of reference, objects on either spinning halo will experience forces from the constant acceleration.

Is it possible for them to stop generating CF and reach equilibrium, yet still spin along their own axis?

If a point on the halo is moving in a circular path, it's essentially accelerating towards the center of the circle and perpendicular to it's current path. To accelerate that object it requires a centripetal force. So no, as far as I can tell, you cannot have a circular moving path without being subject to force.

If it's an arbitrary celestial object, how do you know if it's spinning or standing still?
 

TuxDave

Lifer
Oct 8, 2002
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Originally posted by: Rat
If it's an arbitrary celestial object, how do you know if it's spinning or standing still?

If it was spinning and you were observing it as standing still, then you'd be orbiting around it and thus have a force exerted on you. If it was standing still and you saw it as standing still, you wouldn't be subject to such force. You can also tell by seeing if there was any force besides gravity being exerted on a body on the ring.
 

spike spiegal

Member
Mar 13, 2006
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I highly suggest reading Larry Niven's highly acclaimed "Ringworld", which tries to explain a good deal of the physicc involved.

The 'Rings' in Halo are simply smaller knock-offs of Niven's Ringworld and got their inspiration from it.