12.地球的自传

作者:admin

来源:

2011-12-12 16:37

12.地球的自传

00:00

M:I readly don't understand how you can use the pendulum to demonstrate the rotation of the earth. In fact,your lecture went right over my head.
M:I really didn't understand how you can use the pendulum to demonstrate the rotation of the earth. In fact,your lecture went right over my head.

W:I'd be happy to run through it again. There are two basic principles that you have to keep in mind. The earth rotates around and axis that goes through the north and south poles. Since the surface of the earth is curved,the ground we're standing on right now in the northern hemisphere travels through space in a counter clockwise arc,not a straight line,as the earth turns.
M:I'm just not aware of the movement,because it's relatively slight.

W:Besically,now the other important concept,if you take a piece of string and attach a weight to the bottom, the weight will also swing in a counter_clockwise direction once you set it in motion. Now if you make a pendulum long enough and hang it in a tall building,it will swing very slowly. The weight at the bottom will appear to slowly change its path as it swings back and forth.
Actually the pendulum is moving in a straight line,and it is the earth that is slowly rotating under it.Does that make sense?
M:Well,maybe I need to think about it a little more.Thanks anyway.