Measuring Length

https://www.nist.gov/pml/weights-and-measures/si-units-length

Featuring section 1.5: Accuracy, Precision, Uncertainty & SigFigs

Describe the properties and units of length

What is the base unit of length in the metric system?

The meter was originally defined in 1793 to be one ten millionth of the distance between the North Pole and the Equator through Paris.

Since 1983, the meter has been internationally defined as the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second.

Did you know there are certain measurements that will never be completely accurate? Neil deGrasse Tyson and comic co-host Chuck Nice dive into the minutiae of measurements in this original StarTalk video. Neil tells us why, for certain things, we will never be able to get their exact measurements. Find out about the kilogram and its recent change. We investigate the process of measuring the English coastline. And, you'll hear about the atomic clock – and Avocado's Number.