麻豆传媒

Why does your weight seem to differ if your bathroom scales are placed on carpet instead of a solid wooden floor?
(Continued)

鈥� An earlier answer describing the carpet as an additional spring affecting the scales (16 July) seems to be rewriting .

Essentially there are two springs in series 鈥� the scales, which contain springs, and the carpet, which is springy. If we ignore the weight of the scales, then each spring carries the same load. The carpet simply deforms more than a wooden floor in response to your weight. If we take the earlier respondent鈥檚 argument (that the surface acts as a spring in its own right, 鈥渟oaking up鈥� some of your weight and reducing the reading on the scales) to its extreme, then if the scales were placed on a very compliant surface, your weight would register as zero. But that doesn鈥檛 happen: at some point the carpet is compressed enough for the scales to register the person鈥檚 weight.

Charlie Main, Division of Electronic Engineering and Physics, University of Dundee, Angus, UK