300 million meters per second
It seems unlikely, considering that there are good reasons to consider that the speed of light is an absolute speed limit in our Universe.
Arizona law is confusing. There is a state maximum 85 MPH limit There is a separate law which says that a 55 MPH limit is absolute. There is another law which sets absolute speed limits of 65 and 75 on rural Interstates. In fact the rural Interstate speed limit is 75 ( and the limit on most other rural roads is 65. The maximum posted speed is 75 mph although the primie facie speed limit is 85 mph for rural highway (outside areas of 50,000 or more population). Within city areas such as Phoenix or Tucson the posted limit varies between 55-65 mph although 85 is still the primie facie limit. The 55 as absolute limit is probably left over from the era when 55 was the maximum limit nationwide and is simply a "waste of finite resources" violation.
It is never legal to go above the posted limit. Even when passing a vehicle. That's called an absolute speed law. Only emergency vehicles responding to an emergency may exceed the limit and then only when "reasonable".
826 limit
the posted speed limit
When another speed limit sign is reached that changes the limit from the previously posted one.
The speed limit is exactly that - the speed limit. While a reasonable excess of speed might be overlooked when overtaking another vehicle, there is no guarantee. You can be pulled over and cited for speeding, still.
The posted speed limit is the max speed.
In the UK the speed limit comes into force as soon as you pass the speed limit sign. As such the distance is zero as you should have slowed down to the posted speed limit before passing the sign.
The humps do not affect the speed limit. The speed limit is determined by other rules and signs.
No time limit