INTRODUCTION D Leonardo Da Vinci said: mechanics is a mathematic paradise, because we acquired mathematics's fruit here Galileo(1564-1642) is a German astronomer mechanist and philosopher. He was born in Pisa onFeb15 1564 and died on Jan 8 1642 at the same place. He made a detailed study on the basic concepts of movement including the center of gravity, speed and acceleration and came up with the rigid mathematic formulas. Especially the concept of acceleration is the milestone in the history of mechanics 55 Leonardo Da Vinci said: “ mechanics is a mathematic paradise, because we acquired mathematics's fruit here." Leonardo Da Vinci Galileo Galilei He made a detailed study on the basic concepts of movement including the center of gravity ,speed and acceleration and came up with the rigid mathematic formulas .Especially the concept of acceleration is the milestone in the history of mechanics. Galileo (1564~1642) is a German astronomer,mechanist and philosopher.He was born in Pisa onFeb15 1564 and died on Jan.8 1642 at the same place