The rule of thumb is one car length for every 10 miles per an hour that the car you are driving is traveling.
For example:
You are traveling 70 miles an hour on the interstate, the car you are following should be seven car lengths ahead of you.
When driving, you should always measure your following distance in seconds. A general rule of thumb is to maintain a following distance of at least 3-4 seconds between your vehicle and the one in front of you. This distance allows you enough time to react and brake safely in case of an emergency.
car lengths
You can't measure that..... Los Angeles is already in California!
If you measure the straight line flight distance ("as the crow flies"), the total distance from Atlanta to Norfolk is 504 miles or 811 kilometers.
A direct line between the two cities would measure 3789 kilometres or 2354.4 miles. Using current roads, if driving, the shortest distance between them is 4702.6 kilometres of 2922.1 miles.
It depends on how long a distance you want to measure!
Following distance is typically measured in seconds. A common rule of thumb is the "3-second rule" where you should leave at least 3 seconds of following distance between your vehicle and the vehicle in front of you. To measure this, pick a stationary object on the side of the road, wait for the vehicle ahead of you to pass it, and then count how many seconds it takes for you to pass the same object.
Seconds
You should always measure your following distance by car length. This will give yourself time to break when necessary without being close to the driver ahead of you.
Angstroms
With maths and light brightness.... Distance between two points...
The distance between places.