Gravitational Acceleration in Homogeneous Fields

[jensel]

Hi,

Something which I never read in a physics book.
Let us take a homogeneous gravitational field. Now let's take an appel. Let us watching it falling. Now let's cut it into two pieces. If there would be a very short distance, would we really expect that both pieces now fall slower or faster? Do we really expect, if both pieces have different size, different physics? I wouldn't. Now take two apples and so on. Logically you shouldn't see a difference. I think this thought experiment which I never saw in this context may help to understand physics for undergraduates. Thanks for comments.


Jens

 

[Jonathan Scott]

Hi,

Something which I never read in a physics book.
Let us take a homogeneous gravitational field. Now let's take an appel. Let us watching it falling. Now let's cut it into two pieces. If there would be a very short distance, would we really expect that both pieces now fall slower or faster? Do we really expect, if both pieces have different size, different physics? I wouldn't. Now take two apples and so on. Logically you shouldn't see a difference. I think this thought experiment which I never saw in this context may help to understand physics for undergraduates. Thanks for comments.


Jens

You're right - but that's actually very well known. In particular, that is essentially the same argument that Galileo used when he first worked out that different objects should fall with the same acceleration, in around 1600.

 

[jensel]

You're right - but that's actually very well known. In particular, that is essentially the same argument that Galileo used when he first worked out that different objects should fall with the same acceleration, in around 1600.

I would never say that this thought is new - I just find this point is not teached very well. I found it surprising that a feather falls down the same way as an iron bar, as a child. For me, it was just measured and astonishing and I find "my" little "thought experiment" very convincing. A feather is influenced by friction. I think that those experiments in mind help to understand physics better. If you explain it in more logical way. I found it working well, when I had students. Logical and symmetrical thoughts are not used in teaching very well, that's my opinion (for example to explain sine function etc.) Thanks.