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Terminal velocity is the maximum speed attainable by an object as it falls through a fluid (air is the most common example). It is reached when the sum of the drag force ( F d ) and the buoyancy is equal to the downward force of gravity ( F G ) acting on the object.
The terminal velocity depends on many factors including mass, drag coefficient, and relative surface area and will only be achieved if the fall is from sufficient altitude. A typical skydiver in a spread-eagle position will reach terminal velocity after about 12 seconds, during which time they will have fallen around 450 m (1,500 ft). [4]
This velocity is the asymptotic limiting value of the acceleration process, because the effective forces on the body balance each other more and more closely as the terminal velocity is approached. In this example, a speed of 50 % of terminal velocity is reached after only about 3 seconds, while it takes 8 seconds to reach 90 %, 15 seconds to ...
If correctly selected, it reaches terminal velocity, which can be measured by the time it takes to pass two marks on the tube. Electronic sensing can be used for opaque fluids. Knowing the terminal velocity, the size and density of the sphere, and the density of the liquid, Stokes' law can be used to calculate the viscosity of the fluid. A ...
For example, consider a small sphere with radius = 0.5 micrometre (diameter = 1.0 μm) moving through water at a velocity of 10 μm/s. Using 10 −3 Pa·s as the dynamic viscosity of water in SI units, we find a drag force of 0.09 pN.
The terminal velocity of the particle is affected by many parameters, i.e. anything that will alter the particle's drag. Hence the terminal velocity is most notably dependent upon grain size, the shape (roundness and sphericity) and density of the grains, as well as to the viscosity and density of the fluid.
So, for a human in belly-to-earth position (A = 0.7 m 2, m = 90 kg, C d = 1) this gives 50.6 m/s, about the terminal velocity of the typical skydiver of 55 m/s. The skydiver cannot increase their mass easily enough to significantly increase terminal velocity, and the skydiver's area cross-section is limited by their helmet and shoulders in a ...
Their small size, light bone structure, and thick fur decrease their terminal velocity. While falling, a cat spreads out its body to increase drag. [ 9 ] An average-sized cat with its limbs extended achieves a terminal velocity of about 60 mph (97 km/h), around half that of an average-sized man, who reaches a terminal velocity of about 120 mph ...