Astronaut EDC

not2sharp said:
An astronaut in a stable orbit (neither falling nor pulling away) weighs nothing
Click to expand...

If the astronaut weighed nothing in orbit, that would mean either the earth lost its gravitational field, or he had no mass.
 
Stone Knife said:
The sophisticated space ship repair tool is said to be a hacksaw.
Click to expand...
Yeah, I saw a picture of it yesterday, but damn if I can find it again. :grumpy:

Basically, it was a hacksaw blade, bent at each end to that the middle would sit flush along the tile. The end was wrapped in a blue tape or similar, to avoid puncturing anything; the "handle" was the same, but longer for better grip. The astronaut just lays the saw along the fuselage, and saws off the exposed filler flush with the tile.

The shot also showed a surgical clamp attached to the loose end of the filler strip that was to be cut, I suppose so that it wouldn't just float away. (I'm sure NASA would like to get a look at it, see why it slipped out.)

Very simple, surprisingly low tech, but looks effective.
 
Actually, the bucket does not provide any force in the aforementioned analogy. Whatever tethers the bucket and allows it to be swung around keeping the water in the bucket while it is upside down is providing centrifugal force. Centrifugal force is in the direction away from the axis or center of the arc. Centripetal force is force also along the tether that pulls back towards the axis as gravity does. Tangential force would be the force that keeps an object moving in the same direction or tangent. Centrifugal and centripetal force are non-tangential, meaning they change the direction of the object. When in space, centrifugal and centripetal force tend to cause a cancellation or each others force providing the weighless effect.

Some of you folks paid attention while you were doing your basic science homework. Some of you folks feel better when you get to toss around a few three dollar words. This can also be represented in a formula for those that need to feel important.

W - X = Y

W = the force of knowledge
X = the force of freewheeling jaw movement
Y = why did you bother in the first place

When the force of knowledge is overcome and diminished by the freewheeling jaw that spews forth three dollar words = negative balance of thought or expression which floats away seemingly weightless in space.
 
There is no such thing as centrifugal force. It's a felt effect of centripetal force, created by the motion of a container accelerating in a circle asserting itself against the inertia of a non-tethered body within that container. It is most certainly NOT a force created at the axis of revolution. "Centrifugal force" cannot cancel out centripetal force because it is only a side effect of centripetal acceleration.

Astronauts don't feel acceleration in orbit in any case. Why? Because unlike on the ground, everything inside the shuttle is being accelerated by gravity at exactly the same rate, in exactly the same direction.

There is only ONE force acting on an astronaut in orbit... Gravity. This can be made plain in any force diagram. There is no "tangential force," only tangential velocity. The entire point is that the only effort man need make to maintain orbit at a given altitude is get to a certain speed, and then turn the thrusters off. No force applied tangentially during orbit. No such thing as centrifugal force. The only force acting on the ship and its crew is gravity. And that's really all there is to it. No need to insert bombastic crap in this discussion, I should think.
 
First, they're going to try to pull off the loose piece with their hands (gloves).
If that doesn't work, they'll try forceps (big toothy tweezers).
If that doesn't work, they'll try to cut it with scissors.
If that doesn't work, they'll go the hacksaw route.
 
Hey Knife Saber you need a little schooling. Get a dictionary and you might learn a little something. Dipstick.
 
The original astronaut EDC.

"Randall model 17 "Astro" was especially designed for the seven Mercury astronauts, who carried them on America's first manned space flights. Astronaut Gordon Cooper did the final design, and two of these historically valuable knives are on display in the Smithsonian Institution."

produkt3big.jpg
 
710BMFAN said:
Hey Knife Saber you need a little schooling. Get a dictionary and you might learn a little something. Dipstick.
Click to expand...

I've had a lot of schooling. If you learned your physics from a dictionary that would explain a lot.

(edit: Removed an insult that was immature, however appropriate it might have been)
 
710BMFAN said:
W - X = Y

W = the force of knowledge
X = the force of freewheeling jaw movement
Y = why did you bother in the first place

When the force of knowledge is overcome and diminished by the freewheeling jaw that spews forth three dollar words = negative balance of thought or expression which floats away seemingly weightless in space.
Click to expand...


That's the best thing I've read here yet!
 
knife saber said:
There is no such thing as centrifugal force. It's a felt effect of centripetal force
Click to expand...

A teacher I had used to say that centrifugal force is some kind of "pseudo force", since nothing is really applying it although it is "felt" (as Knife saber says), centrifugal force is indeed an useful abstract conception rather than a real force. Inertia from initial thrust tries to make the astronauts follow a straight path, the earth gravity provides the centripetal force that keeps the astronauts in a curved orbit.


Jaime Orozco.
 
Orozcov said:
A teacher I had used to say that centrifugal force is some kind of "pseudo force", since nothing is really applying it although it is "felt" (as Knife saber says), centrifugal force is indeed an useful abstract conception rather than a real force. Inertia from initial thrust tries to make the astronauts follow a straight path, the earth gravity provides the centripetal force that keeps the astronauts in a curved orbit.


Jaime Orozco.
Click to expand...

I guess that means a centrifuge is a "Pseudo" device used in laboratories across the world. What a dink!
 
"centripetal force and centrifugal force, action-reaction force pair associated with circular motion. According to Newton's first law of motion, a moving body travels along a straight path with constant speed (i.e., has constant velocity) unless it is acted on by an outside force. For circular motion to occur there must be a constant force acting on a body, pushing it toward the center of the circular path. This force is the centripetal (“center-seeking”) force. For a planet orbiting the sun, the force is gravitational; for an object twirled on a string, the force is mechanical; for an electron orbiting an atom, it is electrical. The magnitude F of the centripetal force is equal to the mass m of the body times its velocity squared v 2 divided by the radius r of its path: F=mv2/r. According to Newton's third law of motion, for every action there is an equal and opposite reaction. The centripetal force, the action, is balanced by a reaction force, the centrifugal (“center-fleeing”) force. The two forces are equal in magnitude and opposite in direction. The centrifugal force does not act on the body in motion; the only force acting on the body in motion is the centripetal force. The centrifugal force acts on the source of the centripetal force to displace it radially from the center of the path. Thus, in twirling a mass on a string, the centripetal force transmitted by the string pulls in on the mass to keep it in its circular path, while the centrifugal force transmitted by the string pulls outward on its point of attachment at the center of the path. The centrifugal force is often mistakenly thought to cause a body to fly out of its circular path when it is released; rather, it is the removal of the centripetal force that allows the body to travel in a straight line as required by Newton's first law. If there were in fact a force acting to force the body out of its circular path, its path when released would not be the straight tangential course that is always observed"
 
I think some of you might be confusing centrifugal with centrifical, it is centrifical that does not exist. Also, it is my firm belief that mass never changes. People often confuse mass with weight, even so far as to compare kilograms and pounds. Pounds is a measurement of force and kilograms is a measurement of mass, the two may only be compared when the acceleration do to gravity is known and accounted for. Nevertheless, why are we talking of such stuff in a knife forum?

Let me right the conversation, “I like sharp pointy things!” :D

-Duffin
 
710BMFAN said:
I guess that means a centrifuge is a "Pseudo" device used in laboratories across the world. What a dink!
Click to expand...

Wow, what brilliance. Yep, you've poked holes in our little plot to convince you that things are not quite as they seem to you. I'm certain I'll be seeing a lot of your work coming from these "laboratories" you seem to know so much about. We certainly are dinks. Centrifugal force is a pseudo force? What a crock! And of course, the earth is flat, too. None of that "globe" nonsense for you.

What perception.
What ingenuity.

Bravo.

In case you actually want to learn something, "centrifugal force" only becomes significant as a concept when shifting your frame of reference from outside the revolving system to the revolving thing itself (whatever it may be). In a centrifuge, centripetal acceleration is provided unevenly to the sample in the centrifuge - for a benchtop model the motor rotates the test tubes, which then act against the solution within them. The force the tube contents is just their inertia causing them to smack against the test tube wall. Which is why the pellet in such devices is never flat at the bottom of the tube, it is pressed up against the lower portion of the tube at an angle. Centrifugal force is a "pseudo" force because when it appears, it's completely internal to the revolving object. The existence of perceived forces within the revolving object is simply the interaction of inertia, free bodies, and centripetal acceleration. These pseudo-forces are certainly NOT antiparallel to the centripetal force, and they do not exist for spacecraft in Earth orbit.
 
Duffin444 said:
Also, it is my firm belief that mass never changes.
Click to expand...
Mass can indeed change--that's what provides force to a rocket. As fuel is expended, the mass of the payload changes downward, providing the acceleration.

However, as a measure, mass stays the same whereas weight can change considerably... which is where I believe you were going.

weight = mass * gravity

So if you change gravity up or down, weight changes... whereas mass stays the same.
 
You must log in or register to reply here.
Back
Top