自由落體下落速度

在自由落體的情況下
物體下落的速度與質量無關
因此
兩者同時到達地面

看情況,f=mg 正常我們會講w=mg ,w =weight (重量) ans: 一樣.因物體下落的速度與質量無關,加上2x2x2 )m 的鐵和(2x2x2)m的冰所受的空氣阻力是一樣的,(面積影響空氣阻力) (如不加入空氣阻力)

the ice cube will reach the ground first. although the speed of reach the ground is not related to the mass of the object but it is depending on the air resistance.

the ice cube would melt fall from 20/F, due to the heat generated by the air friction. the ice cube melted and become smaller. so the air resistant is also smaller. therefore the ice cube reach the ground first

同時一齊落地,在地球上的重力加速度是9.81m/s^2(忽略空氣)

同時落地
F=ma=mg
a=g

Air Resistance=bv where m is not dependent

（2x2x2 )m 的鐵

2007-12-25 11:41:05 補充：
F =mg