Motion, Forces and Energy: Chapter 1, Sec 1
Describing and Measuring Motion.
The state in which one object's distance from another is changing.
A place or object used for comparison to determine if an object is in motion.
International system of Units
A system of measurement based on multiples of ten and on established measures of mass, length, and time.
The basic SI unit of length.
The distance an object travel per unit of time.