.......PROPELLING THINGS.......

Sorta - however, there's a bit of a conceptual problem there.

Orbit is not a function of propulsion, it is a function of inertia - the property of an object to remain at rest, or in motion, unless, untill, and in proportion to its being acted upon by an external force.

"Propulsion", as typically understood, entails ongoing input of energy to the end of overcoming inertia. An object in orbit around a planet is not under propulsion. No energy is being expended to maintain its orbital travel; inertia takes care of that. A certain amount of energy was expended to place the object into orbit, but once there, it will remain in orbit without energy input. Essentially, the orbiting object's forward velocity, the speed to which the propulsion mechanism accellerated it, is equal to the downward, or planetward speed imparted by gravity; the object is falling, but its forward momentum is egual to the momentum of its fall.

Depending on the distance of the orbit from the surface orbited, and the presence of an atmosphere surrounding the orbited object, an orbiting object's path of orbital travel may reduce, or decay, drawing closer and closer to the surgace of the orbited object as atmospheric drag - friction - reduces the speed of the orbiting object, eventually dropping that speed low enough that the object no longer orbits, but plummets to the surface of the orbited object, unless propulsion is from time to time applied to maintain the object's forward momentum sufficiently to prevent or counteract orbital decay. Beyond the outermost reaches of a planet's atmosphere, naturally, there is no atmospheric decay - geostationary satellites, for instance, at around 22,500 miles above Earth's surface, require only occaisional propulsive nudges to maintain synchronous orbit, wherein the appear to hanfg stationary above a given point on Earth's surface; their forward momentum, their Earthward momentum, and the rate of the Earth's rotation about its axis are in equilibrium.

Conversely, the application of propulsive force to an orbiting object will cause that object to gain speed, increasing its forward momentum, iand causing the envelope within which the object is orbiting to expand. Again, provided sufficient accelleration is imparted to the orbiting object, its forward momentum will overcome the gravitational force holding it in orbit, and it will proceed to depart from its host - that's how one gets to other planetary bodies - one breaks the Earth's gravitational attraction, ceases falling toward Earth, and progresses in what ever direction it happened to be heading when the speed of the orbiting object relative to the Earth exceeded the pull f Earth's gravity.

omg.. your really smart!
well do you have any ideas then:?

do you think it means what type of energy.. eg: frictional, gravitational or
like petrol, gas etc etc???

could it be potential.. as in the use of a trebuchet>

Well, the question with which you're dealing specifically calls for the types of energy sources used to propell objects through the air. By that parameter, I would say the designer of the question had in mind something on the order of propulsive mechanisms more than energy sources. The energy source might be fuel of some sort, compressed gas of some sort, stored energy of some sort (such as a wound-up spring or rubber band), light energy, as in laser propulsion, orelectromechanical energy, as in ion engines or magnetic propulsion mechanisms. Also included would have to be kinetic energy, such as, for instance, that imparted to an object via the mechanical action of throwing it.

At the end, just about any energy source, provided it is present and applied with sufficiennt force, will achieve the end of propelling an obect through the air, or through the vacuum of space, or through a fluid or liquid. Whatever the source, provided there is enough of it, an object acted upon by the application of energy can be made to move - through just about anything.

A trebuchet's energy is potential only so long as that energy is stored; once the flinging mechanism is released and the arm begins to travel, that stored energy becomes kinetic energy.

The same can be said of a rocket. The chemical energy is only potential until the candle is lit. At that time potential chemical energy is being converted into kinetic energy--

Kinetic energy can be transferred from one form to another---take a sling (biblical not a rubber band sling). The angular kinetic energy is converted to straight line kinetic energy as soon as one side of the sling loop is released (Trebuchets once in motion also use this sling kinetic energy conversion).

Rap

thanks guys think i have a few answers... !!!! about the trevuchet i need to find a diagram???and a ood explanation of how it works??? any ideas?

google 'Backyard artillery'

Rap

THANKS.. i will give it a go....???

you know anything helpful bout trebuchets?

like short explanation of how it works or where to find a diagram>?

Yeah - try Google. If you';re thinking of building one, go for heavy construction and very solid fasteners - lotsa stress involved, and you don't want the puppy tearing itself apart. For a couple hundred bucks in materials, you can launch an average-sized kitchen range a couple hundred yards. Built right, your trebuchet will launch many times, but most of what you launch with it - other than rocks - will only be launchable once.