Agree! 200km/hr is about 56 m/s. A gun bullet travel ~400 m/s wi

來源: 於 2012-06-10 00:07:23 [博客] [舊帖] [給我悄悄話] 本文已被閱讀：次

of ~ 10g. 3.5 kg steel with sharp edge at 200 km/hr is like a bullet 300 time bigger.

Think the other way, how fast you think you can swing a hammer?