Frames of Reference
Discussion
introduction
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
the vomit comet
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:
- Negative-g: (-0.1 g): Approximately 15 seconds
- Zero-g: (0 g) Approximately 25 seconds
- Lunar-g: (⅙ g): Approximately 30 seconds
- Martian-g: (⅓ g): Approximately 40 seconds
| gz (g) | device, event, phenomenon, process |
|---|---|
| −5− | limit of sustained human tolerance |
| −2− | severe blood congestion, throbbing headache, reddening of vision (redout) |
| −1− | congestion of blood in head |
| 0 | free fall, ballistic trajectory, orbit (apparent weightlessness) |
| ~⅙~ | surface of the moon (not accelerating) |
| 1 | surface of the Earth (not accelerating), accelerating at 1 g in deep space |
| 4.5 | roller coaster, maximum at bottom of first dip |
| 3.4–4.8 | partial loss of vision (grayout) |
| 3.9–5.5 | complete loss of vision (blackout) |
| 4.5–6.3 | loss of consciousness (LOC) for most people |
| 6.3 | Tower of Terror roller coaster at bottom of first dip |
| 11.4 | Greg Poe, aerobatic airplane, 2002 |
| 12–14 | ejection seat |
| 16 | R.F. Gray, centrifuge*, 1958 |
| gx (g) | device, event, phenomenon, process |
|---|---|
| 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 |
| 2.0 | HyperSonic XLC (Extreme Launch Coaster) at start |
| 2.96 | Fastest 0–100 km/h by an electric car, average, 2023 |
| 3.81 | Fastest 0–100 km/h by an electric car, peak, 2023 |
| 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 |