Re: Question from grade 11 student

["W. Barlow Newbolt" <wnewbolt@liberty.uc.wlu.edu>]

On Tue, 30 Apr 1996 mdubreuil@musicm.mcgill.ca wrote:

> I'm doing a project  on archimede's law of hydrostatic. Since I'm a scuba
> diver, I went underwater a different depths with a object . My goal is to
> try to figure out if the object's weight changes in proportion with the
> depth.
>
> These were my results:
>
>         Depth          Lenght of my spring (Hook's law   F: k * l
>
>         0  feet                25,2 cm
>         10                      23,9
>         20                      24,5
>         50                      25,2
>
>
> I understand that my object is lighter at 10 feet, but why does it get
> heavier as I go further deep down ?
>
> Marc Desgroseilliers,
> enseignant,
> chef de groupe a la vie etudiante,
> ecole secondaire Dorval,
> commission scolaire du Lakeshore,
> 636-0115
>  ____________,
>
> mdesgroseilliers@musicm.mcgill.ca
I am not sure that I understand what you are doing, but I'll try to 
reply. In water the bouancy on an object should be equal to the weight of 
water which it displaces.  Since water does not compress very much at 
depth I would expect that your object would weight less than in air but 
that the results would not depend very much on the depth in the water.
						Barlow Newbolt