质量守恒定律 自然界的基本定律之一 law of conservation of mass 质量守恒定律一般指物质守恒定律(自然界的基本定律之一) Law of conservation of mass generally refers to the law of conservation of matter (one of the fundamental laws of nature) 拉瓦锡, 现代化学之父 Lavoisier ...
HE FAMOUSLY SAID THAT HE COULD TOPPLE THE EARTH IF GIVEN AN APT PLACE TO STAND ON A lever is a machine consisting of a rigid rod pivoted at a fixed hinge, or fulcrum. In his book On the Equilibrium of Planes , Archimedes proved the law of the lever using geom ...