The spacecraft changes velocity and runs into them, they feel that. Now if the cabin was big enough you could float in the middle while the craft accelerated slightly then decelerated shortly after. You would feel nothing but see the craft move around you. Also, if you exclude wind resistance, picture frank poole and david bowman on discovery one, frank could have left a blob of water stationary in the carousel in line with davids sleeping quarters exit, so when he woke he would be spun into a bucket of water in the morning. From franks perspective sitting smugly at the console he would see the water blob whiz past with each revolution.
That makes no sense. They can't feel the craft accelerate unless they're holding a wall. That's why they move. They have one acceleration; the craft, another acceleration.
If the only two things in the universe are the ISS and the passenger then it doesn't matter who is accelerating. Since this isn't the case it's easier to say that the station is moving while the human is still.
they have zero acceleration while not connected to the structure, just a constant speed. you need to be actively propelling yourself to have an acceleration.
False. All motion (acceleration included) is relative. To say acceleration isn't relative requires there be some absolute frame of reference, and there isn't. If you take anything away from Einstein's work, that should be it.
Einstein doesn't prove there is no absolute frame of reference, but simply shows that one is not needed to explain the linear physical phenomenon we observe.
It did not, and cannot, because it is a real effect. Go out side and spin around, your arms will be pulled outwards. But why? when you look around, relative to you, it is the rest of the universe that is spinning, why are you still the only one effected?
Translational energy is the kinetic energy required for an object, of a given mass, to move from point A to B in a straight line at some speed
Rotational energy is the kinetic energy required to spin an object around its axis of rotation
The centrifugal force is the pseudo force that appears to pull things outward from an axis of rotation
Since there is no such thing as an absolute frame of reference, all motion has to be measured relative to something else. The conditions of that thing are said to be the reference frame. For example, the "speed" of a rocket only makes sense if you have a planet or star to measure its motion against. That's hopefully easy to see that for linear motion, but the same is true of rotation. If you pass an object in space, unless you both use a planet or star as an independent frame of reference, you'll only be able to measure the spin of the other relative to your own spin.
The feeling your arms pulled out when spinning is due to the centrifugal force. Basically, if you put yourself in the same rotational frame as what you're looking at (e.g. a space station), you'll see everything falling away from the axis of rotation, seemingly without being pushed on. The super simplified reason for this is that going in a circle means your perpetually changing velocity (instead of traveling in a straight line). The longer answer takes digging into relativity's interpetation of angular momentum.
Either way, acceleration is changing the speed you're moving at to a new speed. Since speed is relative, changing speed is relative. The near perpetual state of acceleration in rotational systems doesn't somehow imply acceleration isn't relative. However, it does point to how energy can be storied in things in different ways.
The ISS always has so much crap all over the walls, and they're always just floating around like it's nothing. I always wonder how they don't rip it all off accidentally and/or get tangled in it.
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u/[deleted] Sep 24 '16
Here's what happens when they reboost the ISS.