One car length for every 10 miles per hour.
Six car lengths is a good distance.
I always heard of the two second rule but I am not sure if that is law.
1m
one car length per 10 miles per hour
it is recommende to keep a gap of at least two seconds behind the car in front of you so the distance varies with the speed
A safe distance, there is no defined limits of this type as driving near parked cars is situational (at best).
One car length for every 10 miles per hour of speed.
Know your distance between cars, fire hydrants and railroad crossing. These are the most over looked.
The distance between two cars while driving should be at least 2–3 seconds of following distance under normal conditions. This allows enough time to react to any sudden stops or changes in traffic flow. It is important to increase the following distance in adverse weather conditions or when driving at higher speeds.
ten feet
The force of gravity will also depend on the distance between the cars. Choose a suitable distance, then replace the numbers in the formula for gravitational attraction.
Because if you are driving quickly and the driver in-front of you brakes hard then you have more time to react and have a less chance of crashing.