Question

Hello, my question may seem stupid but I was wondering...when Proffesor Walter Lewin measures the metal bar vertically and then horizontally and he finds out it's actually larger when it's horizontally put on the table, I was wondering if that measurement difference won't also affect both rulers as well?, if so, how can we know which is the correct measurement? thanks.

Answer 1

I think Prof. Lewin didn't mean really it's horizontally longer, i think that were an assumption. but the human is really longer horizontally!

Answer 2

It's true. Humans are longer horizontally! And the measured difference has a reason to it, it was his granny's hypothesis.

Answer 3

Humans aren't rigid. Actually, all things are slightly shorter when vertical than when horizontal (when measured in gravity) The ruler will be changed less than the human because it is more rigid.

Answer 4

Doubt solved, thank you very much.

Answer 5

One thing that you are missing here is that the ruler IS of the same length vertically & horizontally, if you DO consider the PRECISION ERROR, i.e. within the limits of measurement. But with the human even within the Precision error we are able to prove that horizontal length IS MORE than the vertical length.

Its true that there will be the force of gravity acting on the Ruler, and THEORETICALLY its length vertically should be lesser than that Horizontally. But PRACTICALLY its negligibly small for a ruler of the order of metres. So your question regarding the change in length of the scale itself is not applicable.