No. Upstream of Teddington, the Thames speed limit is 8kph (approx. 5mph). The rest of the river has no speed limit.
in the river thames
No. Missouri has a speed limit just like everywhere else, and going over that limit (i.e. speeding) is illegal.
not everywhere, but by default there is just a recommended speed (~80mph).
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.
The speed limit is 55mph.
Whatever the posted speed limit is.