英語(yǔ)時(shí)差：哪一個(gè)先落地？（上）

Here’s a physics classic. Suppose you drop a golf ball and a bowling ball from the Empire State Building. Which hits first? Answer? They hit at the same time. You could also have used a marble and a piano and a banana, or any two objects for which air resistance won’t be a big factor. The idea is that everything falls at the same rate, no matter what its mass is. A lot of folks have trouble believing this. It just doesn’t seem right. Oftentimes we say, “But a bowling ball weighs more than a golf ball — doesn’t that 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 more stuff for gravity to act on. In that sense, gravity is pulling on it more. But it still doesn’t fall any faster.