# Human comprehension while moving at high speeds?

Tags:
1. Feb 13, 2016

### Dillon1312

I'm not sure if this is the correct place to ask, but I was looking up some of the fastest vehicles in the world, with the Thrust SSC recorded to have traveled at 771 mph. On top of that many aircraft are capable of moving at speeds over 1500mph.

So I was wondering how well can humans comprehed what they are seeing at those speeds? What would their reaction time be?

Also what kind of G-Forces are they feeling? Is there an equation for calculating G forces at X speed?

2. Feb 13, 2016

### rootone

'G' forces do not result from an objects speed, they are the result of acceleration, (or deccelaration).
I'm not sure on the issue of reaction times, but a pilot flying at Mach 2 or more needs to be in a very alert condition.

3. Feb 13, 2016

### wolram

I should imagine that Andy Green would have to have much faster reactions at 0 ft than a pilot at altitude. I am sure G force is a function of acceleration not speed.

4. Feb 13, 2016

### Borg

G forces have nothing to do with speed. They are due to a change in velocity (speed in a specific direction). For example, astronauts experience around 6 G's at liftoff. Their initial velocity is zero.

5. Feb 13, 2016

### Dillon1312

So if G's are calculated depending upon acceleration, would the equation be G = a/9.8? With a being the acceleration a person is undergoing at that moment and 9.8 being the acceleration of gravity on earth.

6. Feb 13, 2016

### Borg

Take a look Wikipedia g-force article. It will give you a quicker overview of what it is an isn't. Be sure to check the g-force experienced by a top-fuel dragster to see how the forces can combine.

7. Feb 13, 2016

### zoobyshoe

How well you can comprehend something at high speed depends on how far away it is. Things in the far distance can appear to be stationary while things close to you are a blur. The faster you are going the more pronounced this effect: things have to be further away to be comprehensible.

There's a point, obviously, where pilots aren't expected to be able to handle things visually. There's all kinds of instrumentation to guide them.

8. Feb 13, 2016

### Staff: Mentor

Correct.

9. Feb 13, 2016

### jack476

High-speed pilots are given special training to be able to react quickly and stay in control at high speeds. There are also reports of endemic stimulant (provigil and adderall being the drugs of choice) abuse in the Air Force, which might have something to do with it.

But the thing about high altitude is that there isn't really a whole lot to crash into, so it's not quite as dangerous as it might seem.

10. Feb 18, 2016

### jw6661

they build em up...
sorta like you when you are K-12 then college. no one flies 1500 mph for a first timer.

each grade you go up one till reach or weed out. its more reaction than comprehend. sorta like when something throws a ball at you. if you see another fighter jet you find out if its friend or foe... then you either engage or ...

<<Moderator's note: text edited to remove textspeak. Please use proper spellings.>>

Last edited by a moderator: Feb 19, 2016
11. Feb 19, 2016

### jim hardy

What changes at high speed is not reaction time but how far you travel during it.

Dillon you can do an experiment yourself next time you take an airline flight in daytime. Just take a window seat.

"Speed" is perceived by how fast things move across our field of vision.
Watch out the window as the plane takes off
as soon as you get up a thousand feet it seems to slow to a crawl even though the plane is speeding up

If you go through any clouds note how fast the vapors move over the wing's surface.
If you're traveling to someplace warm watch the vapors form around the big flap on rear of wing when pilot flares just before landing.

Once you've reached cruise keep an eye peeled for planes coming the other way. Airliners use 'highways' in the sky marked by radio beacons so you'll probably fly over or above a few. Air Traffic Control keeps them separated by at least a thousand feet vertically, think of lanes one above the other instead of alongside.

You will be AMAZED how fast planes go by in opposite directions.
600 mph is 880 feet per second. That's about top speed of a 757 airliner.
Two such airliners approaching one another each at 880 ft/sec will close a one mile gap in 3 seconds.
From a thousand feet away the viewing angle changes at speed/distance = 1.76 radians per second, or 101 degrees/sec .
Things that are close just whip across your field of vision faster than you can react.

Human reaction time is a goodly chunk of a second.
What changes at high speed is not that amount of time but how far you travel during it. About a city block for an airline pilot, 3X that for a fighter pilot .

Take a window seat and see for yourself. Doesn't cost a bit more.

old jim

12. Feb 19, 2016

### rootone

Another thing that will allow to comprehend how fast an airliner is travelling is to look at the trailing edge of the wing and note how long it takes to pass across a typical small-medium sized town.
It LOOKS slow, but you'll find that you have passed over the whole town in about 30 seconds or less.