What does the term ' g force ' mean ? Why is it often used when discussing the launch or re-entry of a rocket?
831377
it is the force of gravity it's simply 9.8 m/s/s or 32ft/s/s     \nacceleration of gravity is -9.8m/s/s or 32ft/s/s\ng force is just the absolute value
346376
Inertia.\n\nA body at rest tends to stay at rest.  It needs energy to get it moving.  Once moving in a vacuum, it will continue on that course at that speed until something acts on it to change it's speed and direction.  This might be a planet or star's gravity, or a rocket,  or some such.\n\nAccelerating hard to a given speed takes more energy than accelerating slow.  It would take more energy to get a rocket going 1000 mph in 30 seconds than it would to get it going that fast in 30 hours.  The same principle governs your car, and is the reason that you'll get horrible gas mileage if you take off like a jackrabbit to get to 60 mph, vs. accelerating slowly and gently.
96093
I assume that rapid means a large change of acceleration with time.\nThat is described as an Impulse.\nUsually an impulse chalenges the structure of the mass and would tend to break the mass into smaller components.\n\nWhat is called weigth is gravitation forces between two interacting masses.\n\nTo prevent the rocket or airplane to breack appart ,the power that is Invested in these vehicules must be in equilibrium with the power of Gravity at all times.
496244
In the context of molecular mechanics, a force field (also called a forcefield) refers to the functional form and parameter sets used to describe the interactions (potential energy and forces) within a system of particles (atoms or similarly sized objects). It is independent of the system's electron configuration. A force field can be empirical, derived from higher-level modelling (e.g. quantum chemical studies), or even heuristic.\n\nThe name "force field" is a bit of a misnomer, because the "force fields" are actually potential functions, and the actual physical force field is a negative gradient of the potential.\n\nIn physics, gravitation or gravity is the tendency of objects with mass to accelerate toward each other. Gravitation is one of the four fundamental interactions in nature, the other three being the electromagnetic force, the weak nuclear force, and the strong nuclear force. Gravitation is the weakest of these interactions, but acts over great distances and is always attractive. In classical mechanics, gravitation arises out of the force of gravity (which is often used as a synonym for gravitation). In general relativity, gravitation arises out of spacetime being curved by the presence of mass, and is not a force. In quantum gravity theories, either the graviton is the postulated carrier of the gravitational force.[1], or time-space itself is envisioned as discrete in nature, or both.\n\nThe gravitational attraction of the Earth endows objects with weight and causes them to fall to the ground when dropped. Moreover, gravitation is the reason for the very existence of the earth, the sun and other celestial bodies; without it matter would not have coalesced into these bodies and life as we know it would not exist. Gravitation is also responsible for keeping the earth and the other planets in their orbits around the sun, the moon in its orbit around the earth, for the formation of tides, and for various other natural phenomena that we observe.
941619
In simple English...It means that the pull of gravilty is less at 2 points so the orbit expands at those points before being pulled back in by gravity, and so the eliptical shape occurs.
659813
AS THEY TRAVEL from E to M, their weight is zero except when the rocket motors are firing.  Weight is defined as the force applied to a mass by another particular mass in the ABSENCE of acceleration.  Ergo, they weigh differently on M than E because of the difference in the masses of E & M AND the radius at the surface of each body in accordance with the formula given above.\n\nAs I remember, the ratio is about 1/6 for gm/ge at the surface of each.
21267
Gravity is the force of attraction between massive particles. Weight is determined by the mass of an object and its location in a gravitational field. While a great deal is known about the properties of gravity, the ultimate cause of the gravitational force remains an open question. General relativity is the most successful theory of gravitation to date. It postulates that mass and energy curve space-time, resulting in the phenomenon known as gravity.\n\nGravity is acceleration.  means that (if the mass is unvarying) there must be a force that causes a mass to accelerate. For a rocket ship, that is the rocket engine. For the earth, it is the compression of the mass between something on the surface of the earth and the earth's center of mass. The acceleration is in relation to spacetime in that the weight one feels is one's resistance to deviating from one's path in spacetime. The same holds true in the rocket ship except that a rocket engine supplies the force to accelerate an occupant from his spacetime path. There is no difference between the weight he feels because of gravity or the rocket.
881554
Properly named "launch vehicles", these are a class of rockets which are used to launch satellites into earth, moon, sun, or planetary orbits, or, to lauch interplanetary payloads to objects in our solar system.\n\nA launch vehicle can be manned or un-manned. Unmanned vehicles are usually referred to as "Expendable Launch Vehicles (ELVs)", since most of the vehicle is not recovered for re-use. \n\nExamples:\nELVs: Atlas-Centaur, Titan-Centaur\nManned: Shuttle, Saturn V\n\nMore on rockets from Wikipedia:\nhttp://en.wikipedia.org/wiki/Rocket\n\nHope this helps!
147880
>>>Can gravity be used as a means of propultion?\n\nIt can and it is. Have you ever seen a flying squirrel? Or a petrel diving on a fish? They are using gravity as a means of propulsion. \n\n>>>>>For instance if it is possible to create a device which "bounces" off of gravity. \n\nYou can’t ‘bounce off’ gravity. Gravity is an attractive force, not a repulsive. \n\nThe suggestion is nonsense. You might just as well ask whether you can stand at the top of a well and use the hole to fall up to the sky. \n\nOr maybe ask whether you can use the negative speed of a stationary vehicle to get back where you came from. \n\nIt makes no sense in a  ‘sunbeams trapped in a jar as a nightlight’ kind of way.\n\n\n>>>>>somebody said "gravity is an attractive force"\n>>>>> therefore it is a force... so what about the concept >>>>> of anti-gravity?\n\nThat's way outside my ability to comment on. Anti-gravity depends on the production of anti-gravitons. We don't even know if gravity is caused by gravitons yet, we've never seen one. We've ceratinly never been able toproduce an anti graviton. It's all science fiction stuff. I gather it's possible in theory if certain theories are correct, but in practice.....
147623
After releasing the projectile, \n1. The force due to gravity, towards the center of the earth\n   and\n2. The frictional resistive force due to the medium, for example the air resistance.\n\nFor almost all physics calculations for experiment done on earth, the air resistance is considered negligible.\n\nSo the force due to gravity will be the only force acting on a projectile after it is released.\n\nDanEengineer@yahoo.com
875025
How about using it in a sentence and discussing it?\n\nIf an object is dropped from a great height, so that it will fall for a significant period of time, the force of gravity will accelerate the object downward. But as it accelerates, the air through which it passes will resist its motion (wind resistance) with a force that increases as its downward velocity increases. \n\nEventually the object will have been accelerated to a velocity at which the force of wind resistance equals the force of gravity. At that point, the net force on the object is 0 (wind resistance offsets gravity), and its acceleration will also be 0 (F = ma, so in this case 0 = m (0)). The velocity at which this occurs is called the "terminal velocity." It could be called the equilibrium velocity, or the ultimate velocity, or any other descriptive name, but we have come to call it "terminal velocity."\n\nNote that terminal velocity is not a fixed number. Obviously, terminal velocity is rather slow in the case of a balloon (and negative in the case of a helium balloon), since its wind resistance is great relative to its mass. And for a dense, streamlined object (think of a steel spear), terminal velocity would be extremely high, perhaps approaching the speed of sound (Mach 1). \n\nBesides the density and shape of the object, other variables that affect terminal velocity include air density and the force of gravity, both of which are significantly reduced at very high altitudes.
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a) the ground is counteracting the force of gravity, so the rocket is at rest, no other outside forc is acting upon it.\nb) becuase force is applied to the rocket.\nc) becuase of the force of gravity (and friction from air)\nd) if there were no gravity or friction from air
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Force, in physics, any action or influence that accelerates, or changes the velocity of, an object. Force is a vector, which means that it has both direction and magnitude. When several forces act on an object, the forces can be combined to give a resultant, or net force. The resultant force acting on an object, the object's mass, and the acceleration of the object are all related to each other by Newton's second law of motion, named after the 17th-century physicist and mathematician Isaac Newton. The second law of motion states that the acceleration an object experiences multiplied by the mass of the object is equal to the resultant force acting on an object. Thus, if a given force acts on two objects of different mass, the object with a larger mass will have a lower acceleration. See Mechanics.\n\nAn object experiences a force when it is pushed or pulled by another object. For example, shoving a stationary shopping trolley applies a force that causes the shopping trolley to accelerate. An object can also experience a force because of the influence of a field. For example, a dropped ball accelerates towards the ground because of the presence of the gravitational field; electrical charges attract or repel each other because of the presence of an electric field.\n\nUsually, several forces act on an object at once. If multiple forces combine to give a resultant force that is zero, then the object will not accelerate; the object will either remain motionless or continue moving at a constant velocity. For example, if a person pushes a shopping trolley with a force equal in magnitude to the force of friction that opposes the trolley's motion, the forces will cancel, giving a resultant force of zero. As a result, the trolley will move down the aisle with a constant velocity. If the person suddenly stops pushing, the only force acting on the trolley is the frictional force. Since the resultant force is no longer zero, the trolley accelerates: its velocity drops to zero. (An acceleration such as this, in which speed is reduced, is also known as deceleration.)\n\nIn SI units, the unit of force is the newton, which is the force that imparts to an object with a mass of 1 kg an acceleration of 1 m/sec2.
647302
Thrust is the reactive force that is exerted by a rocket, propellar, or jet engine, which propels a craft.
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...mass of the planet it is "escaping" from, and the mass of the rocket.\n\nIf there are other large objects close enough to exert a gravitational influence on the rocket, these may need to be factored in as well.
163543
Since G-Force is a measurement of acceleration, if the spaceship you are in accelerates in space you can feel it.
597906
In school, I used a CAD program to draw and design a rocket made from a soda bottle. In making this, we had to be aware of two important concepts: center of pressure and center of gravity. The center of pressure is the point at which all pressures are centered. This is basically the line at which there is an equal surface area of rocket above and below it.\nThe center of gravity is the line at which there is an equal amount of mass above and below it. For a rocket to fly properly, the center of mass needs to be situated the average diameter of the rocket above the center of pressure.