Maintaining a three seconds gap - or bigger - gives you a basic chance to to brake in time to avoid rear-ending the car ahead if that car should brake suddenly.
A shorter gap doesn't leave you enough time to react to what the car ahead of you does, and make you likely to hit it, if it should brake suddenly.
6-8 seconds
In any driving location, it is generally agreed to be safe if you position yourself 3 seconds or more behind the vehicle in front of you.
Allow more following distance than you would behind another car - three to four seconds - when following a motorcycle to allow the rider enough time to maneuver or stop in an emergency. In dry conditions, motorcycles can stop more quickly than cars.
Distance covered in nth second means the distance covered in that particular second . It cannot be more than the distance covered in n seconds which means the distance covered in a total time of n seconds.
6-8 seconds
2 average car lengths in the standard. The more the merrier. 1 second for every 10 mph. in bad weather 2 seconds
your line-of-sight is greater than 30 seconds ahead
Safe distance is 2 seconds, or 4 car lengths. More if snow is on the ground or its raining.
At minimum 3 seconds. If the road conditions are adverse, it should be 5 seconds or more.
Maintain the same speed as the car in front. Pick an object to use as a reference like a road sign, and as the car in front passed the sign, start counting. If you pass the reference in 3 seconds or more, you are following at a safe distance.
Following distance should be increased (more distance) when behind a motorcycle because (1) the MC can stop faster than a car, and (2) it could go down for many reasons. Greater distance decreases the likelihood of running over the MC.
Use the two second rule. For when, you want to make sure your following distance, look at something on the road that the driver is about to pass by and when they pass by start counting in Mississippis. Stop counting when you pass that thing. The distance between you two should be two seconds or more. You can apply the same rule to the vehicles behind you as well by starting to count when you pass the thing and stopping when the vehicle behind does. Just don't forget to look at the road!