It depends what kind of road you're on and the vehicle you are driving. Any built-up area (anywhere that has street lighting) is 30mph. Dual carriageways are up to 60mph, while motorways are a maximum of 70mph.
1965
the speed limit on a duel carrage way is 345mph.
50cc
The speed limit is the top speed that is legally allowed. If it is exceeded, you are breaking the law.
All vehicles get the speed limit on the road, whether it is a motorcycle motorbike or whatever, it it is a vehicle it has a speed limit.
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.
70
It depends on the average speed which, in turn, depends on what the car is capable of, the speed limit(s), road conditions, traffic, stoppages. At 20 mph, the speed limit on my road, it would take 33.5 days! On a UK motorway, staying within the legal speed limit, just over 9.5 hours.
In practice, It is acceptable to increase the speed of your vehicle over the legal speed limit to pass or overtake another vehicle. Legally, it is not permitted. If the other vehicle is already at the speed limit, you should not be passing it. If it were a police car you were passing, at any speed above the speed limit, they could stop you.
THE LEGAL SPEED LIMIT FOR THAT STREET OR HIGHWAY.
The Speed Limit - 1926 was released on: USA: March 1926 UK: 11 October 1926
In the United States their is no limit, but in other countries their are limits on speed and power.
"Seventy: Speed Limit on a Motorway" (in the UK).