Space has zero friction? so does it need any fuel, once in space?
78721
NO it doesn't - if you're referring only to space - at zero gravity that is! \n\nThe initial launching rocket boosters are abandoned once you enter space, and the fuel is filled only to the suffice the requirement of the rocket launch - enough to push it into space for the rocket to thereon move autonomously.
542734
Meaning moving continually with no additional force needed to overcome frictional or other energy losses.\n\nNo.  It violates the laws of thermodynamics for some process to occur without an energy loss.  If you don't add energy to a system, eventually it will run out of energy.
778567
Constant speed means zero net force.  So what's balancing the air friction?
406464
Yes.  There is a very small amount of matter that enters the atmosphere from space (meteorites), but essentially it is all just being recycled. Some atoms of oxygen you breathe in may have been breathed by a dinosaur, or one of the pharoahs!
79516
engines for space craft don't need to constantly exert forward thrust to keep going, like airplanes. They need to to escape the earth's gravity, but once cleared, they can keep going on forward momentum, using brief propulsion to correct the course of the space craft. \n\nMars and the moon cannot use gasoline based craft, there's no oxygen to burn, so they likely need electric motors, maybe solar powered. Not exactly sure on this but I would say an electric motor of sorts.
964622
If the only things involved in the position of everything in space were momentum and gravity then perhaps all the planets and galaxies and superclusters could have enough momentum to fly away forever like something can have enough momentum to have an escape velocity from the earth.  Also if everything didn't have enough momentum then it would eventually all fall back in together into a "big crunch".\n\nThere is another factor at play, though, in the expansion of the universe called "dark energy" which is something that causes space itself to expand!  So as space itself expands everything in it is carried along outwards with the expansion.  Imagine space is a table and some crumbs on it are galaxies.  As the whole table expands the little crumbs will spread apart from each other.\n\nDark energy is very hard to study and is not well understood.  The sources I cited give good overviews and should give you a better understanding.
625832
I assume this question involves using common sugar (sucrose) are the fuel.\n\nThe answer would depend on how you are extracting the energy out of the sugar as well as just how large of a mass (rocket + ...) you want to move to the moon.\nYour question is far too vague (and meaningless) without A LOT more details.
843756
USE PRINCIPLE OF CONSERVATION OF linear MOMENTUM.\n\nearth gas lower KE because it has huge mass and huge inertia
1023626
the science between the movement of a rocket ship is governed in the third law (i think). The law of action and reaction.\nactually the air acts as a friction. but in space the rocket will fly faster because space is frictionless, due to no air.\nthe flame coming out from its butt's side is opposite to where the rocket is moving.\nthe flame is going < < < = = = \nwhile the movement of the rocket is = = = > > >\nLaw of action and reaction.
677264
I just answered this on another question.\n\nActually, there is no such thing as a true vacuum...Period!\nA true vacuum has never been created, anywhere, where the atomic count is zero.\nThere is always atomic content left to fill the "vacuous" space. No one has ever been able to creat a true vacuum.\n\nContrary to popular belief, empty space is not empty, and it is certainly not a vacuum. \nresearch it, its true.\n"Empty" space actually contains an average of 1 hydrogen atom for every 32 cubic centimeters of space, this data is per NASA.\n\nIn our own Milky Way, space is more dense with 1 hydrogen atom for every 1 cubic centimeter.\n\nAs of today, light has NEVER been propagated through a true empty vacuum. \n\nOne day the misinformation of space, or anything else, as a vacuum will finally die out.\n\nSpread the knowledge
799637
Well simple really, because there is no friction in space once a mass is in motion it will remain in motion.  Newtons law that for every action there is an equal and opposite reaction is applied here.  A plant for instances is in motion and will remain in motion do to there being no friction,  This is known as stellar drift are moon for instances is drifting away from are plant this is do to three things, 1 mass in motion, 2 gravitational pull, and 3rd but not least no friction to stop it from drifting.  So lets apply this to a space ship, it fires it last burst of thrust newtons thirded law is now applied, now in till the ship hits something it will stay in motion do to no friction in space.
275035
There is more friction on re-entry. Friction is geometrically proportional to speed. The shuttle takes a long time to accelerate into orbit, but it comes back full speed. Also the flight angle is diferent on re-entry, exposing more surface.
661933
The thrust of rocket engines are how ships are controlled in space.  Many of the forces that affect air ships (drag, lift, gravity) do not apply since you specified no air or gravity.\n\nTechnically, air ships don't go to space, so there's no real answer to this question.  Richard Branson's Space Ship One recently flew to the edge of space and then landed like a plane, but (as the name indicates) it was a space ship, not an air ship.\n\nAnd there are air and gravity in space.  Gravity holds galaxies, separated by millions of light years, together, so gravity will definitely act on space ships only 100 or 200 miles above the earth.  What causes weightlessness in orbit is not a lack of gravity, but free fall.  The atmoshere is very, very thin at the altitudes where satellites and the shuttle fly, but it is that thin air, causing frictional drag on satellites and the space station, that require constant reboosting to keep them in orbit.\n\nKey to effective flight and control is stabilization, so in addition to moving and turning a ship in space, thrusters also are used to keep it from spinning (reaction wheels also are used for this function).
254807
Even if we define "space" as everything from the ground up, we still only experience a pressure of about 1 kg per square centimeter. That's the pressure--or weight--of Earth's atmosphere. Beyond the atmosphere where empty space lies there is virtually no pressure.\n\nGod is spelled B-I-G B-A-N-G\nPBrax@netscape.com
381192
Rocket Principles\nA consquence of Newton's laws of motion is that for any object, or collection of objects, forces which only involve those objects and nothing else ("internal forces") cannot shift the center of gravity. For example, an astronaut floating in a space suit cannot shift his position without involving something else, e. g. pushing against his spacecraft. The center of gravity--or "center of mass"--is a fixed point, which cannot be moved without outside help (turning around it, however, is possible).\n\nBy throwing a heavy tool in one direction, the astronaut could get moving in the opposite direction, though the common center of gravity of the two would always stay the same. Given a bottle of compressed oxygen, the same result follows from squirting out a blast of gas (a scene that appeared in an early science fiction film). A rocket does much the same, except that the cold gas is replaced by the much faster jet of glowing gas produced by the burning of suitable fuel. At present, rockets are the only means capable of achieving the altitude and velocity necessary to put a payload into orbit.\n\nA rocket engine is a machine that develops thrust by the rapid expulsion of matter. Most rockets today operate with either solid or liquid propellants. The word propellant does not mean simply fuel, as you might think; it means both fuel and oxidizer. The fuel is the chemical rockets burn but, for burning to take place, an oxidizer (oxygen) must be present. Jet engines draw oxygen into their engines from the surrounding air. Rockets do not have the luxury that jet planes have; they must carry oxygen with them into space, where there is no air.\n\nThere are a number of terms used to describe the power generated by a rocket. \n\n\nThrust is the force generated, measured in pounds or kilograms. Thrust generated by the first stage must be greater than the weight of the complete launch vehicle while standing on the launch pad in order to get it moving. Once moving upward, thrust must continue to be generated to accelerate the launch vehicle against the force of the Earth's gravity. To place a satellite into orbit around the Earth, thrust must continue until the minimum altitude and orbital velocity have been attained or the launch vehicle will fall back to the Earth. Minimum altitude is rarely desirable, therefore thrust must continue to be generated to gain additional orbital altitude.\n\nThe impulse, sometimes called total impulse, is the product of thrust and the effective firing duration. A shoulder fired rocket has an average thrust of 600 lbs and a firing duration of 0.2 seconds for an impulse of 120 lb-sec. The Saturn V rocket, used during the Apollo program, not only generated much more thrust but also for a much longer time. It had an impulse of 1.15 billion lb-sec.\n\nThe efficiency of a rocket engine is measured by its specific impulse (Isp). Specific impulse is defined as the thrust divided by the mass of propellant consumed per second. The result is expressed in seconds. The specific impulse can be thought of as the number of seconds that one pound of propellant will produce one pound of thrust. If thrust is expressed in pounds, a specific impulse of 300 seconds is considered good. Higher values are better. A rocket's mass ratio is defined as the total mass at lift-off divided by the mass remaining after all the propellant has been consumed. A high mass ratio means that more propellant is pushing less launch vehicle and payload mass, resulting in higher velocity. A high mass ratio is necessary to achieve the high velocities needed to put a payload into orbit.\n\nThere are three categories of chemical propellants for rocket engines: liquid propellant, solid propellant, and hybrid propellant. The propellant for a chemical rocket engine usually consists of a fuel and an oxidizer. Sometimes a catalyst is added to enhance the chemical reaction between the fuel and the oxidizer. Each catego
284291
If you could shoot a rocket into outer space with enough force to cause it to leave our solar system, perhaps it would exhibit "perpetual motion" and travel forever.  But that would be deceptive.  It would continue to move unchanged only because it meets little matter or force to overcome.  On earth, to set something into motion you must add to its kinetic energy which equals one half times its mass times its velocity squared.  It doesn't matter how you add the energy (or that it gains more say by falling) we are interested only in the energy you added to create perpetual motion.  It could revolve say suspended above powerful frictionless magnets within the vacuum inside an evacuated bell jar for a very long time.  However, there is no perfect vacuum on earth and there would still be atoms or molecules that would collide with and slow down the rotating item whether that took hours or days or years.  Perpetual motion must last forever(!) without you or Nature adding to its original kinetic energy.  If you hold your hand outside a moving car you will feel wind on your hand and some reasoon it could be harnessed (like a sail boat) to propel the car, neglecting the fact that the wind exists solely because the car is burning fuel.  Out of gas = out of wind.\n\nI would encourage you to pursue your theory for the lessons involved but carefully account for all the energy.  Consult with any engineer (especially mechanical at first) or any physics teacher (professor) and remember that your theory could involve a better use of energy if not perpetual motion.  You must patent most devices within a year of public disclosure (which would not include a witness to your theory or device).  Good luck.
605786
When a spacecraft is in orbit it needs no energy. That's the simple answer. However, you need to get it into orbit in the first place, and this means accelerating the object to the speed it needs to orbit the earth - around 18,000 mph. How much energy you need then depends on the mass of the object or spacecraft - this can be calculated from 1/2 mv^2. \n\nTo escape the earths gravity altogether the spacecraft needs to go faster, about 25,000 mph or 7 miles per second. So if you were going to Mars for example, once you achieve that speed you need no more energy.