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Creeping flow past a falling sphere in a fluid (e.g., a droplet of fog falling through the air): streamlines, drag force F d and force by gravity F g. At terminal (or settling) velocity, the excess force F e due to the difference between the weight and buoyancy of the sphere (both caused by gravity [7]) is given by:
A space vehicle's flight is determined by application of Newton's second law of motion: =, where F is the vector sum of all forces exerted on the vehicle, m is its current mass, and a is the acceleration vector, the instantaneous rate of change of velocity (v), which in turn is the instantaneous rate of change of displacement.
Similarly, the force is proportional to the square of the mass of the object. One of these terms is from the gravitational force between the object and the wake. The second term is because the more massive the object, the more matter will be pulled into the wake. The force is also proportional to the inverse square of the velocity.
In fluid dynamics, the drag equation is a formula used to calculate the force of drag experienced by an object due to movement through a fully enclosing fluid. The equation is: F d = 1 2 ρ u 2 c d A {\displaystyle F_{\rm {d}}\,=\,{\tfrac {1}{2}}\,\rho \,u^{2}\,c_{\rm {d}}\,A} where
The downward force of gravity (F g) equals the restraining force of drag (F d) plus the buoyancy. The net force on the object is zero, and the result is that the velocity of the object remains constant. Terminal velocity is the maximum speed attainable by an object as it falls through a fluid (air is the most common example).
Viscous drag of fluid in a pipe: Drag force on the immobile pipe decreases fluid velocity relative to the pipe. [ 4 ] [ 5 ] In the physics of sports, drag force is necessary to explain the motion of balls, javelins, arrows, and frisbees and the performance of runners and swimmers. [ 6 ]
In low Earth orbit, the force due to drag is many orders of magnitude more dominant than the force imparted due to gravity gradients. [8] When a satellite is utilizing aerodynamic passive attitude control, air molecules from the Earth's upper atmosphere strike the satellite in such a way that the center of pressure remains behind the center of ...
The force between a fluid and a body, when there is relative motion, can only be transmitted by normal pressure and tangential friction stresses. So, for the whole body, the drag part of the force, which is in-line with the approaching fluid motion, is composed of frictional drag (viscous drag) and pressure drag (form drag).