Some Physics Facts.

Physics is a science of measurement. Standard units of measurements are needed so that every body is using the same method. Mass, length, time and temperature are the basic units. The metric system is the SI system. In SI length is metres, mass is kilograms, time is seconds and temperature is kelvin. Length is the distance between two points. Mass is the amount contained in a body. A gap between two events is time. Degree of hot or cold is temperature. Estimates are not reliable. That's why measurments are needed.