how do jet engines provide a forward thrust for an airplane?
596792
Jet engines work on Newton's 3rd law. Throw sometihng back with a certain force and you will be propelled by that same force.\n\nNow, by continuity eqn, Av = A'v'\n\nIf you throw something out of a small area at a high velocity, the rate of flow in the opposite direction is then proportional.
532059
When planes fly west to east, they can often go into the jet stream, which can add 100 or more miles per hour to their speed.  When flying in the other direction, they must fight this wind.  At the very least, they can fly above or below it, which reduces its effect, but they still have a ground speed of less than planes flying the other direction that can use the jet stream's assist.\n\nIt's the difference between trying to row a boat upstream vs. downstream.
1070904
A compressor or supercharger pressurizes the intake air in an engine. This fits more air into the cylinder, enabling it to burn more fuel. So you get more power from a given size engine. In piston-engine airplane, it lets the plane fly higher, where the atmosphere would otherwise be too thin.\n\nA turbocharger is the same thing, but it uses a turbine that is powered by engine exhaust to run the compressor.
1039578
Its because of the Jet Stream.
510383
Jet engines are very precisely calibrated and need a higher octane fuel (regular car fuel is about 83-97 octane, the efficiency at which it burns).
997128
Actually yes\n\na small aircraft, can in fact stop forward movement over the ground.  If the plane is flying into the wind at 70 mph, (indicated air speed) however the wind  he is flying into, is hititting his plane at 70 mph, that would put the ground speed of zero.  All aircraft are effected by wind.  The same plane flying at a air speed of 70 mph, with a tail wind of 70 mph, has a ground speed of 140 mph.\nalso\nA landing is also known as a controlled crash.....think about it
520546
The sail acts like a wing that creates a certain forward force on the boat, regardless of its forward speed.  If the resistance to the motion (mostly water drag) is low enough, the boat can easily go faster than the wind.  Certain ice boats (with only runners for drag) have exceeded 100 mph with a 20 mph breeze.
54343
Try wikipedia next time:\n\nThrust vectoring is the ability of an aircraft or other vehicle to direct the thrust from its main engine(s) in a direction other than parallel to the vehicle's longitudinal axis. The technique was originally envisaged to provide upward vertical thrust as a means to give aircraft VTOL or STOL capability. Subsequently it was realised that the use of vectored thrust in combat situations enabled an aircraft to perform various maneuvers not available to conventional-engined planes.
59236
Aircraft are able to climb and maintain altitude by utilizing a combination of the Bernoulli effect and simple momentum transfer in the air flow to generate lift. Lift is generated primarily by the wing of the aircraft. \n\nTo generate lift using the Bernoulli effect, the cross-section of the wing is shaped in such a way that the distance from the leading edge to the trailing edge is greater along a path that runs over the wing than under the wing. As the aircraft is propelled forward, air necessarily flows both over and under the wing. Because of the greater distance that air must travel over the wing, the air pressure over the wing is less than the air pressure under the wing. This difference in pressure between the top and bottom of the wing results in a net upward force, or lift, on the wing. This is the Bernoulli effect. \n\nOne way of understanding the physical basis of the Bernoulli effect is to consider that, since the path of the air flow over the wing is longer, the air over the wing is forced to expand into a greater volume than that flowing under the wing. Consequently, the air pressure over the wing is necessarily lower than that under the wing. \n\nLift can also be generated by dynamic momentum transfer from the airstream. In this method, the tilt, or angle of attack, of the wing relative to the overall direction of motion causes the flow of air striking the under surface of the wing to be turned, or deflected, downward. That is, a downward momentum is imparted to the airflow by the deflection induced by the wing. Newton's law dictates that a compensating reaction force (lift) acts in the upward direction on the wing according to F = dp/dt, where p is the momentum (F and p are vectors). This is the same principle that generates sufficient upward force on water skis to keep a skier from sinking below the surface. \n\nIn practice, the aerodynamics of flight are complicated by many other effects. Obviously, opposing the upward lift is the downward force of gravity. Likewise, opposing the forward thrust of the aircraft is the backward force of drag created by resistance to passage through the air. Also, both the Bernoulli and momentum transfer effects depend upon the smooth, or laminar (streamline), flow of air around the wing. Various factors can induce turbulence in the air flow that (generally) spoils lift, increases drag and decreases the overall efficiency of the aircraft in flight. \n\nFor more details, see the web site: \n\nhttp://www.aviation-history.com/theory/index-theory.html
465068
As the plane's engines provide thrust, there is a certain amount of force countering it in the form of drag. So if the thrust from the engines were to drop off, the drag force would be greater than the forward force. (Eventually, the drag force will also be reduced so that the two opposing forces will be in balance again.) Because of this, the plane will immediately start to decelerate.
508347
It needs air to fly.  However, it can use very thin air.  One idea for using the space plane is to fly it out of the atmosphere, where its engine will cease to function.  The plane then glides as far as it can outside the atmosphere.  As it begins loosing altitude (because it is on a suborbital trajectory) it reenters the atmosphere and the SCRAM jet engine will work again.  It keeps skipping across the top of the atmosphere this way until it reaches its destination.\n\nThis trick saves a lot of fuel because aerodynamic drag is minimal while the plane is outside the atmosphere.
805626
OK, I'll try to help you learn the principle so you can pass the test. My explanations are in ().\n\nA high tech jet car speeds along the desert floor at a constant velocity of 180 miles/hr north.a) what is the net force on the jet car? the jet car hits some sand which causes a drag force on the car of 5000 N to the south. The computer instantly compensates so the jet exerts a thrust force on the car of exactly 5000 N to the north at the same time the car hits the sand. The jet car now... choose ALL that apply: \n\n(There has been drag all along. Since the car has been going at a constant velocity, the car's jet has to be exerting an equal and opposite force to compensate for the drag. If the drag and thrust are equal and opposite there's no net force. Newton's 1st says it will stay in motion at the same speed in the absence of a net force. So now, the net force = 5000 N - 5000 N = 0.) The car \n\nmaintains constant velocity\nmoves with constant non-zero velocity\n\n(I explained all this above.)\nNewton's first law states: When the __ net force__ on an object is zero, the object will __maintain__ constant __velocity__.\nAnother way of saying this is that, if the total force on it equals zero, an object's _acceleration__ will also be zero.\n\nIs it necessary to apply a force to keep an object going in a circle at constant speed? \n\n(The object will want to keep going at constant speed in a straight line because of inertia - without a net force it will do that. The force required to go in a circle is towards the center.)\n\nYes, because the __velocity__ is changing.
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.
1054432
I don't remember very well I but I red somwhere about a F1 car beating a F16 fighter on a 2km distance.\n\nLet's take an example: \nRoughly a 747 weight about 400tons and has 4 engines of 25tones of thrust. This would lead to a maximum acceleration of 0.25Gs at take off. I'm sure a fast car can do better than that
1110236
Airflow over the lifting surfaces creates pressure differences between top and bottom sides, which gives you the lifting force.  You have to shove the lifting surfaces through the air in order for them to generate the lift, though, hence why true aeroplanes must have engines to push them along.   If you don't have an engine then you are a glider, and barring thermal upcurrents you will be perpetually falling.   Until...\n\nI think passenger jets can glide at about a 1:20 downward slope with no engine power.
733139
It follows Newton's law that for every action there is an equal and opposite reaction.  It's usually a wheeled vehicle that flings something backward in order to move forward.  The simplest type uses the jet of air escaping from an inflated balloon.
354185
The short answer is, the same way all fixed wing aircraft do.\n\nWings on aircraft product lift, by taking advantage of something called Bernoulli's Principle. It says, in essence, that faster moving air causes air pressure to be lowered. You'll notice that the upper surface of aircraft wings are curved, and have more length to them than the underside of the wings. Since the airflow over the wing's surface has a greater distance to go on top than on bottom, the speed of the airflow is faster on top of the wing, hence lower pressure.\n\nStill, the best designed wing in the world won't help an aircraft get airborne without something known as the thrust/weight ratio. The P-47 was a very heavy aircraft in its day, but had a massively powerful radial engine that produced more than enough thrust to get it airborne and let Bernoulli's Principle take over...\n\nA great aircraft with an impressive war record.