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Late addition: This is also why Project Orion -- the ultimate low-tech nuclear rocket engine -- would have worked. Build a huge shield, mount your craft to it with shock absorbers, and set off an atom bomb on the far side. The part of the bomb's shock wave which hits the plate will drive the craft forward.
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If there is no friction in space, then how does the space...
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Nov 12, 2018 · By conservation of momentum. When the thruster expels high velocity gas in one direction, that gas has momentum. Since there is no external force acting on the system, the total momentum of the system (thruster and expelled gas) cannot change. Thus, the thruster must acquire an opposing momentum such that the total momentum is unchanged.
Momentum in Space. The demonstrations in this clip show collisions which occur in a closed (no mass enters or leaves) and isolated (no external force acts on the bodies) system. There are two types of collisions to consider: elastic and inelastic. In an elastic collision the kinetic energy of the colliding body can change but the total kinetic ...
- Lift
- Mass
- Mass Flow Rate
- Dynamic Pressure
- Effect of Velocity on Aerodynamic Forces
- Effect of Air Density on Aerodynamic Forces
- Student Airfoil Interactive Simulation
Lift is created by deflecting a flow of air, and drag is generated on a body in a wide variety of ways. From Newton’s second law of motion, the aerodynamic force F on the body is directly related to the change in momentum of the fluid with time t. The fluid momentum is equal to the mass m times the velocity Vof the fluid.
Since the air moves, defining the mass is tricky. If the mass of fluid were brought to a halt, it would occupy some volume in space. We can define the density (r) of the fluid to be the mass divided by the volume v.
Since the fluid is moving, we must determine the mass in terms of the mass flow rate. The mass flow rate is the amount of mass passing a given point during some time interval t and its units are mass/time. We can relate the mass flow rate to the density mathematically. The mass flow rate mdot is equal to the density times the velocity times the are...
The aerodynamic force equals a constant times the density times the velocity squared. The dynamic pressure of a moving flow is equal to one half of the density times the velocity squared. The aerodynamic force is directly proportional to the dynamic pressure of the flow.
The velocity used in the aerodynamic equation is the relative velocity between an object and the flow. The aerodynamic force depends on the square of the velocity. Doubling the velocity quadruples the force. The dependence of lift and drag on the square of the velocity has been known for more than a hundred years. The Wright brothers used this info...
The aerodynamic force depends linearly on the density of the air. Halving the density halves the force. As altitude increases, the air density decreases. This explains why airplanes have a flight ceiling, an altitude above which it cannot fly. As an airplane ascends, a point is reached where there is not enough air mass to generate enough lift to o...
You can investigate the effect of momentum on lift by using the Student Airfoil Interactive Simulation.Set a small angle of attack using the slider, then vary the “Speed” and “Altitude.” Try doubling the speed and notice the effect on lift. Change the altitude until the air density is half of its previous value. What happened to the lift? You can u...
Aug 31, 2024 · However, it does have mass and interacts with other objects that have mass through gravitational effects. Dark matter also experiences angular momentum. It's another reason everything in space is ...
In a sense, the outside air is like a cork in the engine. It takes some of the pressure generated inside the engine just to exceed the ambient outside pressure. Consequently, the velocity of combus-tion products passing through the opening or throat of the nozzle is reduced. The good news is that as the rocket climbs into space, the ambient ...
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Mar 18, 2019 · Thus, you can push with the same force that you'd push a lighter object with, but for longer, since the object won't fly away immediately. And since you applied the same force but for a longer period of time, you'll have delivered more momentum to object you pushed, and will have gained more momentum in the opposite direction.
