時差N小時:哪一個先落地?(上)

Here’s a physics classic. Suppose you drop a golfball and a bowling ball from the Empire StateBuilding. Which hits first? Answer? They hit at thesame time. You could also have used a marble and apiano and a banana, or any two objects for which airresistance won’t be a big factor. The idea is thateverything falls at the same rate, no matter what itsmass is. A lot of folks have trouble believing this. Itjust doesn’t seem right. Oftentimes we say, “But abowling ball weighs more than a golf ball — doesn’tthat mean gravity is pulling on it more?” Well,there’s a distinction to be made here. The bowling ball has a greater mass, so there’s morestuff for gravity to act on. In that sense, gravity is pulling on it more. But it still doesn’t fallany faster.

這是一個物理學(xué)的經(jīng)典：設(shè)想你從帝國大廈上同時丟下一個高爾夫球和一個保齡球。那個先著地?答案?它們同時著地。你也可以換成彈子，鋼琴或是香蕉，或任意2個受空氣阻力影響不大的物體。任何物體都會以相同的速度落地，無論質(zhì)量多大。許多人不太相信這個規(guī)律。這個規(guī)律只是看起來不對。我們經(jīng)常會說“但是保齡球要比高爾夫球重很多——那并不表明重力會更多作用于較重的物體嗎?這里要說明下區(qū)別。保齡球的質(zhì)量更大，所以引力作用的面積會更多。那樣的話，引力會更大，但是物體落下的速度并沒有變快。

classic n. 杰作 marble n.彈子 facto n.因素 distinction n.區(qū)別