what is meant by a standard unit of measurement? why is it necessary to have standard units of measurements? name the SI unit of length.write it's symbol.

Standard unit of measure for length in the U.S. is miles, and in the rest of the world, it is kilometers. On a smaller scale, such as measuring the length of a pen, we use inches in the U.S. and centimeters in the rest of the world. Other U.S. measurements that we use for length are feet and yards.

Units of measurement are the terms that we use to describe the size of something. You probably know that units include things like seconds, kilograms, meters, and so forth.

Without standard units of measurement, scientists would have a huge problem understanding what other scientists were saying. After all, if I were to refer to a meter as "the length of my leg" and another scientists were to refer to it as "the length of a Saint Bernard dog", we'd have a lot of trouble when it came to do actual science. To avoid this problem, the SI system of units gives us a convenient and, more importantly, standard set of units that we can agree on.