IGCSE/GCSE/O & A Level/IB/University Student Forum

Qualification => Subject Doubts => GCE AS & A2 Level => Sciences => Topic started by: Ghost Of Highbury on February 25, 2011, 06:13:59 am

Title: Physics Doubt - Deformation of solids
Post by: Ghost Of Highbury on February 25, 2011, 06:13:59 am

Paper : Winter 2007, paper 2

Question 4)c)

I dont understand the use of a bubble in there. Plz help

Title: Re: Physics Doubt - Deformation of solids
Post by: Sue T on March 14, 2011, 11:50:34 am

the thing is the bubble in there is smthin u dont want - its like a handicap or its jus tht smthin went rong wen makin the rod and ths bubble ended up in it -- so they're asking u the maximum area of this useless bubble so tht the rod dsnt break (hope th idea is clear)
so if the force applied is 1.9x10^3  N
the maximum stress (above which it'll break) is 9.5x10^8
since stress=froce/area
     max stress= force/minimum area of rod
     so ur min area of rod ends up being = 2x10^-3
     the rod is already 3.2x10^-3
     so the difference must be th max area of the bubble
subtract the two u end up with 1.2x10^-3