Jet force

Jet force is the exhaust from some machine, especially aircraft, propelling the object itself in the opposite direction as per Newton's third law. An understanding of jet force is intrinsic to the launching of drones, satellites, rockets, airplanes and other airborne machines. Jet force begins with some propulsion system; in the case of a rocket, this is usually some system that kicks out combustible gases from the bottom. This repulsion system pushes out these gas molecules in the direction opposite the intended motion so rapidly that the opposite force, acting 180° away from the direction the gas molecules are moving, (as such, in the intended direction of movement) pushes the rocket up. A common wrong assumption is that the rocket elevates by pushing off the ground. If this were the case, the rocket would be unable to continue moving upwards after the aircraft is no longer close to the ground. Rather, the opposite force by the expelled gases is the reason for movement.

Jet force is the exhaust from some machine, especially aircraft, propelling the object itself in the opposite direction as per Newton's third law. An understanding of jet force is intrinsic to the launching of drones, satellites, rockets, airplanes and other airborne machines. Jet force begins with some propulsion system; in the case of a rocket, this is usually some system that kicks out combustible gases from the bottom. This repulsion system pushes out these gas molecules in the direction opposite the intended motion so rapidly that the opposite force, acting 180° away from the direction the gas molecules are moving, (as such, in the intended direction of movement) pushes the rocket up. A common wrong assumption is that the rocket elevates by pushing off the ground. If this were the case, the rocket would be unable to continue moving upwards after the aircraft is no longer close to the ground. Rather, the opposite force by the expelled gases is the reason for movement. θ is constantly changing as the aircraft moves around. At any given moment, however, the cosine of this angle θ will give us the component of the force that is acting in the forward direction. Multiplying the total force by this cosine of θ would yield the thrust: \text{Thrust} = \text{Jet Force} \times \cos\theta Because θ ranges from 0° to 90° and the cosine of any angle in this range is 0 ≤ cos θ≤ 1, the thrust will always be either less than or equal to the jet force- as expected, as the thrust is a component of the jet force. For lift, however, we are looking for the vertical component, rather than the forward component. The sine of angle θ will give us the component of the force acting in vertical component. Multiplying the jet force by the sine of θ will yield the lift: \text{Lift} = \text{Jet Force} \times \sin\theta Similar to cosine, the sine of an angle ranging from 0° to 90° will always between at least zero and at most one. As such, the lift will also be less than the jet force. Of jet force, lift and thrust, we can find any one of these if the other two are given using the distance formula. In this case, that would be: \text{Jet Force} = \sqrt{\text{Thrust}^2 + \text{Lift}^2} As such, jet force, thrust and lift are inherently linked. \text{Weight} = mg In this equation, m represents the mass of the object and g is the acceleration that is produced by gravity. On earth, this value is approximately 9.8 m/s squared. When the force for lift is greater than the force of weight, the aircraft accelerates upwards. m_1 v_1 + m_2 v_2 = m_1 v_{1f} + m_2 v_{2f} In this situation, m 1 represents the mass of the gas in the propulsion system, v 1 represents the initial speed of this gas, m 2 represents the mass of the rocket and v 2 represents the initial velocity of the rocket. On the other end of the equation, v 1f represents the final velocity of the gas and v 2f represents the final velocity of the rocket. Initially, both the gas in the propulsion system and the rocket are stationary, leading to v 1 and v 2 equaling 0. As such, the equation can be simplified to the following: 0 = m_1 v_{1f} + m_2 v_{2f} After some more simple algebra, we can calculate that v 2 (the velocity of the rocket) is the following: v_{2f} = -\frac{m_1 v_1}{m_2} This gives us the velocity of the aircraft right after it takes off. Because we know all forces acting on it from this point on, we can calculate net acceleration using Newton's second law. Given the velocity that the aircraft takes off with and the acceleration at any point, the velocity can also be calculated at any given point.

Text derived from https://en.wikipedia.org/w/index.php?oldid=1188290015 under CC BY-SA 4.0; modifications have been made.