can you explain what terminal velocity is?

Answer 1

The terminal velocity of an object falling towards the earth, in non-vacuum, is the speed at which the gravitational force pulling it downwards is equal and opposite to the atmospheric drag (also called air resistance) pushing it upwards. At this speed, the object ceases to accelerate downwards and falls at constant speed. An object moving downwards at greater than terminal velocity (for example because it previously used power to descend, it fell from a thinner part of the atmosphere or it changed shape) will slow until it reaches terminal velocity.

For example, the terminal velocity of a skydiver in a normal free-fall position with a closed parachute is about 195 km/h (120 mph or 54 m/s). This velocity is the asymptotic limiting value of the acceleration process, since the effective forces on the body more and more closely balance each other as it 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 reach 99% and so on.

Higher speeds can be attained if the skydiver pulls in his limbs (see also freeflying). In this case, the terminal velocity increases to about 320 km/h (200 mph or 89 m/s), which is also the maximum speed of the Peregrine Falcon diving down on its prey.

The reason an object reaches a terminal velocity is that the drag force resisting motion is directly proportional to the square of its speed. At low speeds the drag is much less than the gravitational force and so the object accelerates. As it speeds up the drag increases, until eventually it equals the weight. Drag also depends on the cross sectional area. This is why things with a large surface area such as parachutes have a lower terminal velocity than small objects like cannon balls.

Note that the density increases with decreasing altitude, ca. 1% per 80 m (see barometric formula). Therefore, for every 160 m of falling, the "terminal" velocity decreases 1%. After reaching the local terminal velocity, while continuing the fall, speed decreases to change with the local terminal velocity.

Answer 2

Terminal Velocity is the maximum speed an object can attain when falling. The main factor involved is wind resistance. As demonstrated on the moon, a hammer, and a feather will fall at the same speed,(no atmosphere). Add an atmosphere, and that all changes.

Answer 3

As you go faster and faster the resistance you encounter from the air/wind increases. When you are finally at a speed where the restistance from the wind equals the force that is propelling you, in most cases gravity, you stop accellerating and you stay at a constant velocity ... that is called the terminal velocity, the velocity at which you stop accellerating.

Answer 4

DOOM is correct, but I thought you might like to see some pertinent equations to go with the narrative explanation.

f = ma = W - Fd; where f = net force on a freely falling body, m = mass of said body, a = acceleration of the body, W = mg = weight of the body, and Fd = drag forces acting counter to the weight.

Fd = 1/2 Cd rho A v^2; where Cd = coefficient of drag, rho = density of the gas (air), A = cross sectional area of the body, and v = velocity of fall. As DOOM pointed out, Fd depends on the density of the air, which does in fact get larger with decreasing height above ground. Also, as DOOM pointed out, if the cross sectional area (A) is decreased by pulling in one's arms, Fd can be decreased.

So as rho gets bigger during the fall, Fd gets bigger and the net f = ma gets smaller for a fixed weight (W). Thus, the falling body slows down all other things equal. Conversely, when A gets smaller, Fd lessens and the W - Fd = ma = f net force get bigger and, all other things equal, acceleration gets bigger (the falling body speeds up).

v = terminal velocity when f = ma = W - Fd = 0; that is, when the drag force equals the weight of the falling body so that a = 0 and the body no longer accelerates. However, as pointed out by DOOM and me (above) terminal velocity is not a constant; it changes with altitude (rho changes with altitude) and with the cross sectional area (A).

Answer 5

It is the speed at which accelerating force equals drag force, and a body reaches a steady speed. For an object falling under gravity, it is the maximum free fall speed reached.

Answer 6

Both Doom and Eyeonthescreen have excellent and complete answers to the question. I would really look at thier answers and not consider some of this other information which is mostly incomplete or inaccurate.

Answer 7

The speed at which an object balances out and doesn't increase in speed from a 32 feet per second per second.Somewhere around 125 MPH.

Answer 8

When the gravity acceleration equals the wind resistance.

Answer 9

T.V. is the fastest speed that an item reaches during freefall!

Answer 10

http://www.slvhs.slv.k12.ca.us/~pboomer/physicstextbook/physglossary.html

try this its really good reference