Why Do You Need to Know Velocity

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SPECULATIVE Science

Why is it necessary to travel 11km per second to escape the earth's gravity (escape velocity), when surely whatsoever speed volition do, as long equally you keep going up?

Luke, Wellington NZ

• If you commencement at less than xi km/southward at ground level and don't go any further 'push' (ie you irksome down as you go up, like a stone thrown into the air) you will fall to the ground once again. If you start at more than 11 km/s, you will never come downwards.

  Phil Cohen, Sydney Australia

• In a way, you are right. if you went straight upward at any speed, eventually you would get so far from the earth that the effect of the Earth'southward gravity was negligable. All the same, where the 11km per 60 minutes comes in is that it is the speed at which an object, rather than being held in orbit effectually the earth or falling back to it due to gravity, volition be thrown outwards past sufficient centrifugal force to describe an open up curve abroad from the planet.

  John Ramsey, Hackney United kingdom of great britain and northern ireland

• Providing that you can continue your propulsion organization going and the thrust is greater and so gravitational pull dorsum to Globe, yes any speed will practise. One time you reach escape velocity however you are going fast enough to escape the Globe's gravitational pull without doing any more work, you lot can plough your engines off and yous'll nevertheless go on going never to return.

  John Gresham, Waterloo Merseyside

• Escape velocity is calculated on the supposition that the only strength applying is gravity, that is, only after the rocket engines (or whatsoever accelerated you to 11km/s) have stopped firing. Imagine yourself above the World's atmosphere travelling away from the Earth at high speed. Earth's gravitational pull is slowing you downward, simply as your distance from World increases, that pull weakens. If you were initially travelling at less than the escape velocity and then eventually Earth'south pull would exist enough to bring you to a cease and from then you on you would fall back to Earth. The escape velocity is the speed you need to avoid this fate and keep travelling forever, although you would need to travel at a much higher speed if you wanted to accomplish the stars in your lifetime.

  M Baillie, Sawston Uk

• If you throw something up in the air, information technology will bear on ascension until the force of gravity overcomes the velocity of the object and causes it to continue slowing until it stops and then starts falling back to earth. Y'all are kind of correct in saying that you merely need to "keep going upward", just in order to keep going upwardly yous need a sufficient amount of velocity to overcome the force of gravity. The corporeality of velocity needed to escape our planets gravity is approx 11km per second, which is known equally escape velocity.

  Steve, London Great britain

• The term "escape velocity" refers to the initial velocity of an object (at the surface of the Earth). The supposition is that no further strength is applied to the object one time it has set off. If the object starts at less than 11 km/sec, eventually the gravitational pull of the planet volition pull it dorsum to Earth before information technology escapes gravity. Of course any velocity will exercise if connected force is practical to the object, just as a machine being driven uphill will keep going if enough power from the engine is applied via the accelerator.

  Jeremy Marchant, Stroud United kingdom

• It isn't necessary. As you lot say, whatever speed volition practice. Escape velocity is but the speed that theoretically would be sufficient to remove something from World's gravitational influence with no further impulse required.

  Michael Fisher, Brisbane Australia

• Escape velocity is the speed required to escape gravity in the absence of any force being practical. To go on going upward requires the continual awarding of strength. So yeah, of course it is possible to keep going upward and further from the earth, simply without reaching escape velocity y'all would eventually be pulled back to earth when the fuel runs out.

  Clive Gordon, Ruislip UK

• Escape velocity is literally the velocity which an object would need to exist projected in lodge to leave the surface of a planet or other body in space. If the object were subjected to a steady upward force just greater than its weight,instead of an explosion,it would eventually leave, only much more slowly. Information technology is interesting to note that the speed of air molecules is also depression to permit them to escape the Earth, but greater than the Moon'south escape velocity. That's why nosotros have an atmosphere and the Moon hasn't. Is this rocket science?

  Alan Shepherd, Huddersfield UK

• You lot're right, but escape velocity is the speed a projectile (i.e. unpowered lump) would require to escape the World'due south gravity field. If you have enough power you can trundle upwardly at your leisure. This indicate was ably covered in the onetime Peter Sellers movie "mouse on the Moon" which had a steam kettle spaceship. Rockets ordinarily just have to get high enough to fall into orbit. However, you do need to get a rocket upwardly to a high velocity before its fuel runs out if you want to send a probe to another planet.

  Craig Napier, Eagle Heights Australia

• It is non necessary to travel at 11km/s to escape the earth's gravity, any speed will exercise, as long as you keep going up. 11km/south is known every bit escape velocity considering a body travelling upwards at this speed at the earth's surface will proceed going up without any further force being applied; the opposite argument (that y'all must achieve escape velocity to keep going up) does not follow, but anything travelling more slowly volition demand a bit of a push on the way up.

  Phil Barker, Edinburgh Scotland

• The escape velocity refers to an the speed an object needs to achieve to movement from its current point in a gravitational field to infinity(as the gravitational field has no distinct cease indicate), information technology is equal to the speed that the object would exist traveling at if it was pulled by the same gravitational field from infinity to that same point. Notwithstanding this only applies for an unpowered mass that would be constantly decelerating due to the gravitational pull of the plant and you are quite correct in saying a powered mass would be able to escape no matter what its speed.

  Steven, Glasgow

• You'd have to go up a very long manner indeed to escape the earths gravity. Remember that this is what holds the moon in its orbit. An orbiting object has not escaped gravity, information technology is in constant freefall towards the world. As long as information technology goes fast enough, it never reaches the ground because the globe curves abroad below it.

  Howard, Haywards Heath West Sussex

• In theory, you're right, and if just Everest was taller, you could climb information technology all the way up to orbit as slowly equally you damn pleased. Let's assume there's two means into infinite, the slow way and the quick way. The ho-hum way is to have some sort of propulsion engine, at least big plenty to lift the vehicle'due south weight (e.g. a modernistic jet fighter can easily climb vertically, at speeds of 500MPH). The problem is that the jet engine can't go the oxygen information technology needs after nearly 5 miles up. The answer is to use a rocket motor, which carries all the fuel & oxygen it needs. Only that turns out to be a lot of fuel (a HUGE lot of fuel) that you would be carrying, all the way up to 25,000 miles loftier or then where gravity becomes negligible and where, ideally, the final drop of fuel runs out. That brings us to the quick way: use that fuel in one quick outburst, advance to 11km per second (25,000 MPH) as fast every bit possible, so coast the rest of the way with empty tanks and a dead engine. That way, you're conveying spare fuel for the shortest possible time.

  Paul Reilly, London United kingdom of great britain and northern ireland

• You are right, but in order to "keep going up" on sustained ability you'd have to carry immense reserves of fuel to push yous upward. When Isaac Newton start described the concept of escape velocity he was thinking of a ball shot from a cannon. And modern rockets are much like that, their fuel tanks can just push them up for a few minutes and from and then on they have rely on their own inertia. If they don't accomplish escape velocity by then, they fall back or remain in orbit.

  Alejandro Pareja, Madrid Spain

• True, in theory any speed would exercise. But in practice the difficulty comes from the merchandise-off between the rate at which you escape the Earth's gravity and the rate at which you consume the fuel needed to do then - and hence the fuel needed at take-off. If you lot ascended at 5mph, but had the typical fuel capacity of the shuttle and would be largely used upward in 10 to 15 minutes, yous'd simply get up a couple of miles.

  Martin, Manchester UK

• Escape Velocity is the minimal velocity required to escape earth's gravity without applying whatsoever further strength. In this case, when whatsoever speed is maintained continuously a forcefulness is constantly applied. And then the central point is the Strength applied.

  Shravan Singh, Kolkata India

• An unpowered projectile needs escape velocity to travel arbitrarily high but a continually powered vehicle does not, of course. When the vehicle is in orbit above the temper nigh whatsoever force will exercise to button information technology further out - hence the ability of puny ion drives to push craft into higher orbits. It'south getting into orbit that takes all the power. A thou space lift is proposed to accept the craft out to where the orbital speed is the rotation speed of the Earth's surface, and so doing away with the flashy rocketry. Don't hold your breath.

  miles.felton, berkshire

• The 11 km/hr is the minimum speed necessary at the surface of the globe, to enable travelling any arbitrary distance from the globe without whatever means of propulsion. Yet, you are quite right that, if you take means of propulsion, such as a rocket ship, you tin can travel as slowly away from the surface as you like.

  Michael Hall, Canberra Australia

• A stone thrown upwardly would demand to achieve this speed, nevertheless the space shuttle coule become upward equally dull every bit required (Bold enough fuel reserves). The distinction is whether the flight is powered or not.

  Lee, Leeds United kingdom

• There is a big difference between an object being aimed vertically upwards and shot out of a cannon and a powered rocket. The ball shot from the canon receives energy but as information technology passes through the barrel, from then on it is unpowered and slows downwardly as it climbs through the earths gravitational field. Escape velocity refers to this case, non a powered rocket. Incidentally the mass of the ball does not effect the escape velocity if in that location is no atmospheric friction, which ways that an elephant and a mouse would both have to exist given the same escape velocity if launched from the surface of the moon!

  Chris Folland, Moshi Tanzania

• The term escape velocity presupposes that the object being considered is not subject to any external acceleration/forcefulness other than gravity. Equally such an object travels upwards information technology will of class exist slowed past gravity, merely at the same fourth dimension an object that moves upwards from the world the event of gravity gradually dimishes. If yous begin travelling up besides slowly gravity will bring you back down to earth. If you start out travelling fast plenty, whilst gravity will slow you down it will non exist sufficient to bring you dorsum downward to globe. The escape velocity is the pause point between these two alternatives.
  The escape velocity is of course dependent upon the altitude from the earth (or indeed any large trunk), diminshing as you travel away. Therefore if you lot started the world's surface and travelled upwards at the escape velocity, although your velocity would diminish due to gravity it would still remain at what would exist defined as the escape velocity.
  You could of grade escape from earth's gravity if you could continuously move at even a very low speed. The trouble is maintaining this speed confronting the pull of gravity. To do so you would demand to innovate some other force, at which indicate the concept of escape velocity is no longer applicable.

  Paul Hoad, Sutton, UK

• At 11km/south you can successfully break orbit and escape the gravitational pull of the Earth. At 10km/south the World volition eventually slow down your ascent till you brainstorm falling back towards the ground. These values are at basis level. Once in orbit the escape velocity is lower than 11km/s. The greater the planet mass the greater the gravitational pull. To accept off from the surface of MASSIVE Jupiter a rocket would need to be travelling at around 40 miles per second!! To escape the sun it is effectually 400 miles per 2d! To escape a black hole you would have to travel beyond 300,000km/south - faster than the speed of light - which is impossible. That is why light cannot even escape from the surface!

  Paul Steele, Marske, UK

• Escape velocity is an energy thing. If you're going at escape velocity you don't demand any more energy to escape from the Earth, because your kinetic energy is already enough (bold you don't lose it; for example air drag). But you tin can get more slowly if y'all either spend more than energy, or if you go ballistic from higher altitude.

  Ian Woollard, Uk

• So how practice you explicate a helium filled balloon with no thrust and no persistent velocity, travelling at minimal speeds and still being able to exit World gravitational pull, bold no gas is lost and the balloon remains in tact? 'Floating' into infinite would non require dandy thrust or huge amount of fuel but requires a helium to rocket ratio of at least 1:000000000001 recurring

  Thomas, Croydon England

• If we are talking about the planet of earth, the escape velocity is the speed master needed to first a shell at the top, in this case must be the top speed of 11 km / s to end upwardly outside the World's atmosphere, and therefore nosotros can say that it is the speed of liberalization of gravity.

  Abdulah . I . Meftah, Farasan Islands, Saudi Arabia

• You're all wrong. The technology exists and has been used to escape earth's atmosphere at a much slower speed. Nevertheless, the engineering science is highly classified and is only available to a select few.

  Drewey Whittaker, Albany Ga United states

• Every bit per everyone (bated from the Area 51 theorist at the end), in that location's no reason why you can't provided your acceleration is >nine.8 m/s so you volition travel abroad from the Globe for as long as the fuel lasts. Ane betoken nobody has made is that gravity is dispatch and to beat it y'all need opposite acceleration (something your chair is doing at them moment), so you would be accelerating abroad from world. The closest Lagrange betoken (areas of apartment space-time) of the moon would be the obvious target equally you wouldn't and so be pulled back to earth - considering otherwise Globe's gravity will just take too long to reduce sufficiently - and anyway, you'd be stuck in deep space. Equally the fuel weighs a considerable amount, and needs sizable containers, in that location are efficiency reasons for burning it all equally quickly every bit possible while dumping spent containers en road - standard rocket style. That said, a slow rocket would demand to provide constant >10m/southward thrust for the 300,000km or so information technology takes to go to your target L1. If your dispatch is a measly 12m/s (ii.2m/southward net acceleration), then even though L1 is 90% of the distance to the moon, by the halfway point you probably would have sufficient momentum to coast to L1. Even at 100km distant, gravity is only reduced by near 3% then it'southward not a major consideration. Notwithstanding, your rocket wouldn't have to endure such huge tolerances, and I approximate the structure could therefore exist much lighter. Ok, now I might be making Mr Area 51 sound sensible but I'chiliad beginning to see traction in a variant of the thought... Perhaps someone could correct me, just if a rocket accelerated directly upwards (not orbital acceleration equally usual - I mean it's the same Newton requirement after all), burnt fuel reasonably apace but never reaching anything like 25K, simply enough to drift to a near stop at say L4, then couldn't we slingshot it on L4 (is information technology possible to slingshot a convex Lagrange? Surely it is.), slingshot the moon and so Globe, could escape velocity be reached more efficiently that way? Or say if you lot're going to the moon, why provide more than free energy than the journey requires past insisting on reaching EV with a orbital route? Am I missing something hither?

  David, Peterborough, United Kingdom

• This is a large question - Can a Infinite vehicle have say three weeks to get to the Moon only travelling at a far slower speed. What is the fuel required to do that and would information technology be possible ? The high velocity used at the moment is get into orbit around the world however if you wanted to travel to the moon couldn't you do it slower but over a longer period of fourth dimension ? Obviously if yous didnt go into orbit effectually the moon yous would take to be able to slow downward and then that you wouldn't crash into it. Information technology does seem that if you had more time you could do things at slower pace

  Roy, Cape Town South Africa

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Source: https://www.theguardian.com/notesandqueries/query/0,,-197342,00.html

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