Which ever you find easier. Find a fixed point ahead i.e. a telegraph pole. As the car in front passes it, in good driving conditions, say to yourself at normal speed, "Only a fool breaks the two second rule!" If you passed the pole before you finished it, you are too close to the vehicle in front. If you finished it way before you reached the pole, you are too far away from the vehicle in front. The two second rule mantra automatically adjusts the distance between vehicles dependent on speed. However, you must increase the distance by at least 50% for wet/slippy conditions. Repeating the first half of the phrase will do that.
It is generally recommended to measure the distance in seconds rather than feet or car length when following another vehicle. This is because measuring in seconds provides a more accurate representation of the time it takes to react and stop in case of sudden braking. It also allows for a consistent measurement regardless of the speed of the vehicles involved.
I would use a centimetre to measure the length of a boy. Not sure what a boy yard is, though.
You could measure the length or width of it but you would have a decimal. You should be using centimeters.
Microscope
You can't convert between units that measure completely different things. In this case, length and time.
The length of your foot should but not on everyone. The average person's foot measures up.
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.
It is more like car length than seconds when following another car. You should be at least 2 car lengths from the other car.
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.
There are no "following" units, but I would use metres.
I would use a centimetre to measure the length of a boy. Not sure what a boy yard is, though.
You should use a meter stick to measure the length of a soccer pitch.
Millimeters or centimeters.
It is not seconds, but car length. If you are seconds behind someone and they stop fast you will hit them.
One.
A naked cat
Length is measured in meters in the metric system.
To convert seconds to feet, you need to know the speed or distance being traveled. Without that information, you cannot directly convert seconds to feet.