Motion was first understood by Galileo in the 17th century.
Galileo made careful experiments and compared his predictions to those experiments. He invented or greatly refined water clocks to make the time measurements he needed. In understanding motion -- esp'ly free fall -- Galileo observed balls rolling down inclined planes. As the planes became steeper and steeper, his results more closely approached those of free fall.
Galileo may be called the Father of Modern Science because of his emphasis on experimental results. The correctness of a scientific theory must be based upon the agreement of its predictions with experimental results.