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The Physics Hypertextbook © 1998–2013 Glenn Elert |
No condition is permanent.
Newtonian relativity: absolute linear motion at a constant velocity cannot be detected, nor can absolute rest. All motion is relative to a frame of reference. It is not possible to distinguish motion with a constant velocity from rest. All constant velocity frames of reference are equivalent (including frames of reference that appear to be at rest — after all, a prolonged state of rest is motion with a constant speed of zero).
Finish
KC-135
The maneuver can be modified to provide any level of g-force less than one g. Some typical g-levels used on different tests and the corresponding time for each maneuver are as follows:
| gz (g) | event or symptom |
|---|---|
| 16 | R. F. Gray, centrifuge*, 1958 |
| 12–14 | ejection seat |
| 11.4 | Greg Poe, aerobatic airplane, 2002 |
| 4.5–6.3 | loss of consciousness for most people |
| 3.9–5.5 | complete loss of vision (blackout) |
| 3.4–4.8 | partial loss of vision (grayout) |
| 4.5 | roller coaster, maximum at bottom of first dip |
| 1 | surface of the earth (not accelerating), accelerating at 1 g in deep space |
| ⅙ | surface of the moon (not accelerating) |
| 0 | free fall, ballistic trajectory, orbit (apparent weightlessness) |
| -1 | congestion of blood in head |
| -2 | severe blood congestion, throbbing headache, reddening of vision (redout) |
| -5 | limit of sustained human tolerance |
| gx (g) | event or symptom |
|---|---|
| 0 | stationary or moving at a constant velocity |
| 0.4 | "pedal to the metal" in a typical American car |
| 0.8 | "pedal to the metal" in a high performance sports car |
| 1.7 | "pedal to the metal" in a Formula One race car |
| 2 | Extreme Launch™ roller coaster at start |
| 3 | space shuttle, maximum at takeoff**; jet fighter landing on aircraft carrier |
| 8 | limit of sustained human tolerance |
| 31.25 | R. F. Gray, centrifuge*, 5 s duration, 1959 |
| 40 | USAF chimpanzee, centrifuge*, 60 s duration, 1956 |
| 35–40 | J. P. Stapp, rocket powered impact sled, 1 s duration, 1954 |
| 60 | chest acceleration limit during car crash at 48 km/h with airbag |
| 70–100 | crash that killed Diana, Princess of Wales, 1997 |
| 83 | E.L. Beeding, rocket powered impact sled, 0.04 s duration, 1958 |
| 247 | USAF chimpanzee, rocket powered impact sled, 0.001 s duration, 1957 |
| 3400 | flight data/voice recorder, impact acceleration limit |
| * | The passenger capsule of a human centrifuge pivots so that a test subject in a seat would experience a vertical acceleration while a test subject lying down would experience a horizontal acceleration. |
| ** | During lift off, the space shuttle (which is pointing more or less upward) is accelerated in the direction of its vertical axis, but the passengers (who are hanging upside down in their seats) are accelerated in the direction of their horizontal axes. |
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The Physics Hypertextbook © 1998–2013 Glenn Elert |
No condition is permanent.