物理学史上最美的十个实验第八名VIP免费

物理学史上最美的十个实验第八名Galileo'sexperimentswithrollingballsdowninclinedplanes伽利略的斜面滚球实验Galileocontinuedtorefinehisideasaboutobjectsinmotion.Hetookaboard12cubitslongandhalfacubitwideandcutagroove,asstraightandsmoothaspossible,downthecenter.Heinclinedtheplaneandrolledbrassballsdownit,timingtheirdescentwithawaterclock—alargevesselthatemptiedthroughathintubeintoaglass.Aftereachrunhewouldweighthewaterthathadflowedout—hismeasurementofelapsedtime—andcompareitwiththedistancetheballhadtraveled.Aristotlewouldhavepredictedthatthevelocityofarollingballwasconstant:doubleitstimeintransitandyouwoulddoublethedistanceittraversed.Galileowasabletoshowthatthedistanceisactuallyproportionaltothesquareofthetime:Doubleitandtheballwouldgofourtimesasfar.Thereasonisthatitisbeingconstantlyacceleratedbygravity.伽利略继续提炼他有关物体移动的观点。他拿了一块大约六米长，廿五厘米宽的木板，中间挖了一个平滑的沟槽。他先将木板斜放，将许多铜球沿沟槽滑下，再用水鐘计算球落下的时间。铜球滑行的距离各有不同，最后一一比较。亚里士多德曾预言滚动球的速度是均匀不变的：铜球滚动两倍的时间就走出两倍的路程。伽利略却证明铜球滚动的路程和时间的平方成比例：两倍的时间里，铜球滚动4倍的距离，因为存在恒定的重力加速度。