What is the fastest potential speed of any naturally falling object ?

Question

If objects are falling from the sky, whether they are rain drops or aircrafts, what is the fastest recorded speed ? Can they max out there speed and simply not get any faster or do they continue to increase in speed ? If they continue to increase, what is the fastest possible speed, assuming the least resistance ?

So, in response the potential best answer (#16), the highest speed is 220 mph if dropped from a height of 66000 km, the approximate end point at which gravity is a factor. So, based on this answer, terminal velocity if approximately 220 mph and an object with least possible resistance, theoretically, could only decend at 220 mph ?

Answer 1

the speed of falling objects on earth is limited by the forces of friction it encounters in the air.

so, the max speed depends on the mass and size of the object, its shape and also the height from which it started (if you start falling from space, you will get a higher max speed since there's less air in space to slow you down)

now, a few examples:
- human being falling from a plane: 180km/h before parachute opening, but you can get up to 1000km/h if you fall head first
- rain: 0.1cm/s to 800cm/s (3.6 m/h for very fine drops to 28.8 km/h for heavy rain)

Answer 2

Objects that drops from the sky (such as from an aircraft) will be constantly accelerated by gravity towards the ground. Without air-resistance, their vertical speed will increase by approximately 9.81 m/s each second.

Air-resistance will try to reduce the speed of the object. Air resistance increases with speed, so at small speeds it's almost neglible. As the speed increases, air-resistance becomes more and more important.

As the falling object is constantly accelerated by gravity, it will gain higher and higher speed, but when it goes faster, air-resistance will slow it down. After some time, an equilibrium will be found, and the object will travel with constant speed towards the ground. That speed depends upon the air-resistance of the object, compared to it's mass. Small heavy objects will have higher top speed than large light objects (e.g. a stone falls faster than a feather).

A large rain-drop can fall up to 9 m/s, whereas a small rain-drop will fall much slower, such as 2 m/s. A falling human will fall approximately 55 m/s. As all of these objects consists mostly of water, it is their size and shape that will define their maximum speed. Larger objects fall faster than smaller objects, since they have less air-resistance compared to their mass.

Also, one can increase speed by having the right shape. A skydiver that goes head first and tries to minimize air-resistance can go well beyond 55 m/s. The world record is 143 m/s. Using balloons to go higher than is possible from an airplane, and using specially designed "suits" (or armors, whatever...) to reduce air-resistance, skydivers have been able to go as fast as 319 m/s. This is faster than the speed of sound.

Of course, specially designed airplanes and rocket planes have been known to go even faster, as would a large ball of lead, if you dropped it from the same balloon as the skydiver.

The fastest objects falling into the atmosphere come from space. These are accelerated not just by earths gravity, but also by the suns gravity, which is much more powerful (we don't feel the gravity from the sun, since we are in orbit around it). In addition, there is very little air-resistance in space (there is some resistance, as space isn't totally vacuum, but compared to earth, it's completely negligible). The speed of asteroids can vary dramatically, but their average speed is said to be 25 kilometer/second!

Once an asteroid comes into earths atmosphere, it will be rapidly breaked by the atmosphere (air-resistance). This will heat the asteroid up, and cause the outer layers to vaporize. Most asteroids burn up before they reach the earth. If they are large enough, they might hit the earth, and cause significant damage. The impact of a large asteroid is believed to once have made dinosaurs and most other life on the earth extinct.

If we go back to the more theoretical question of only using Earths gravity to accelerate an object, and assuming no air-resistance, the maximum speed that can be achieved is 11.2 km/s (about half that of the "average" asteroid). This number is the same as the earths "escape velocity", a number rocket scientists use to describe how fast you must accelerate a rocket before it will leave the earth completely (i.e. not return to earth, and not go into orbit). Unfortunately, this is of only theoretical interest, as the main problem for rocket scientists is travelling through the earths atmosphere, not simply reaching high enough speeds.

Oh, by the way, if you are confused by the unit m/s, remember that 1 m/s = 2.2369363 mph = 3.6 km/h. So 55 m/s = 2.24 * 55 mph = 123 mph = 3.6 * 55 km/h = 198 km/h.

Answer 3

186,300 miles per second (the speed of light). This is purely hypothetical as to reach this speed would mean the object was falling for an immense distance (light years) and would have to be falling towards some gigantic body that had a gravitational pull that extended light years away from it's surface - no such body exists, the nearest would be a black hole.

However, using a real model (planet earth). Acceleration due to gravity is 9.81 metres per second per second. This means that if something is falling then after 1 second in freefall it will be travelling at 9.81 metres per second, after another second it will have increased by a further 9.81 metres per second.

To make the math easy let's round up 9.81 to 10.0. If something is in freefall for 15 seconds then it will be travelling at 150 metres per second (15 x 10). The distance it will have travelled can be taken by multiplying the time by the average speed.

As it started with a speed of 0 and is now travelling at 150 metres per second the average speed will have been 75 metres per second. As the object has been falling for 15 seconds it will have travelled a distance of 1,125 metres (75 x 15).

So far so good (I hope). The problem is that the further away from the surface of the earth you get the less gravity there is.

Newton's law of gravity tells us that the force decreases with the square of the distance. Now, the surface of the earth is approximately 6,400km from the centre of the earth. So if you were to go into space some 6,400km from the earths surface then gravity would be one quarter of that on the surface (you're twice as far from the earths centre as on the surface and 2 x 2 = 4).

If you were to go to 12,800km the gravity would be one ninth (you're 3 times the distance that the earths surface is from the centre and 3 x 3 = 9).

If we go to 10 times the distance (64,000km from the earths surface) then gravity will be one hundredth of that on earth and the acceleration due to gravity would be just 0.0981 metres per second. We'll ignore anything beyond 64,000km as the gravity would be so weak as to be negligible.

So the question is - if something was dropped towards the earth from a height of 64,000km how fast would it be going when it hit the earths surface.

By doing a bit of mathematics the answer works out to be approximately 360kmh or 220mph. This assumes that there is no friction or air resistance which of course there is. In reality the speed will vary depending just what the object is. A javelin for example would reach close to 360kmh / 220mph, a human being would perhaps be about 200kmh / 120 ph and a tree with lots of leaves and branches might reach 150kmh / 90mph. Eventually there comes a point when the amount of resistance is the same as the gravitational pull and the object won't accelerate any further (known as terminal velocity).

If you want to test the math please borrow the space shuttle and drop a tree from 64,000km up - just don't do it over my house please.

Answer 4

Falling Speed

Answer 5

Because friction which exist when an object falls and the friction force depends on speed, there is a maximum velocity, which can be reached in air, water etc. - an object reaches velocity which simply is the value at which resistance is equal to the gravitational force. I think it was called terminal velocity. In the air it was somewhere around 100 - 300 km/h for common objects, depending on object falling. Factors that matter is mass, area and drag coefficient (depends on shape).

Answer 6

Falling to earth, there is no limit short of light speed, but there is a practical limit on the order of 100,000 mph. Ignoring air resistance, an object striking earth from outer space (and not already in earth orbit) will have a velocity of at least 25,000 mph (escape velocity). To this must be added any velocity that the object had before it neared earth. Since almost any such object must have been in orbit around the sun, its orbital velocity would be added (vectorially) to the escape velocity; if it is going much faster than 75,000 mph, it will be going too fast to remain in solar orbit (at least anywhere near earth).

Answer 7

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The heavier object will have the higher potential energy as you know it (U = mgh) Reason: From the Universal law of gravitation, heavier mass will get a greater force of attraction from the Earth. Putting in different words, it'll have greater potential to meet to the Earth(ONLY BECAUSE OF ITS HIGHER MASS) than the smaller mass. Now, we both agree that after reaching to the ground, potential energy of both masses become equal (to 0). Higher mass has higher ability to do the work but it doesn't mean that it should have higher velocity; it only means that it will have HIGHER KINETIC ENERGY. Now, the law of nature is such that kinetic as well as potential energy both are directly proportional to the mass of the body. So, for the conversion of potential energy to kinetic, the factor 'm'(mass) gets cancelled out and we are always left with velocity, v = root(2gh).

Answer 8

the object accelerates until it reaches terminal velocity. Terminal velocity is the maximum speed which can be reached by a falling object, since the only force driving a free falling object is gravity, and it is a constant force, the object will acclerate until its drag force is equal to the force acting on it. Terminal velocity is different for each object, based on its weight and shape. However for a person it is about 120 mph.

Answer 9

I'm not sure of the exact numbers but what you are referring to is Terminal Velocity. I believe a human being falling within the Earth's atmosphere TV is somewhere around 120 miles per hour (176 feet per second).

Terminal Velocity is the point at which a falling body achieves a maximum speed and stops accelerating.

Don't listen to all the yoohoos who didn't read your question correctly and put down 9.8 meters per second squared. That is free fall acceleration but they forgot that once the object gets to a certain speed it does not increase 9.8 meters per second per second anymore. It stops accelerating.

Check this action out: http://en.wikipedia.org/wiki/Terminal_velocity

So, given a mass, as the density of the fluid the body travels through, and the drag coefficient approach zero the terminal velocity approaches infinity

Answer 10

- Clearly the maximum speed of any body is "terminal velocity" - by definition - but that doesn't really answer the question.

Given the parameters of the question ("assuming the least resistance") we are clearly assuming falling body in a vacuum. Therefore, the maximum possible speed must be the universal speed limit: a number approaching the speed of light, or c.

And yes, don't buy the 9.8 m/s/s number - that's an acceleration not a speed.