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

Qualification => Subject Doubts => GCE AS & A2 Level => Sciences => Topic started by: Igcseboy on April 25, 2010, 09:43:24 am

Title: Edexcel unit 2 physics help!!!!
Post by: Igcseboy on April 25, 2010, 09:43:24 am

Question 21 c (ii)

june 2009 unit 2

helpp urgentsss

Title: Re: Edexcel unit 2 physics help!!!!
Post by: astarmathsandphysics on April 25, 2010, 10:01:07 am

R=pl/A and V=lA so A=V/l
R=(pl/(V/l))=pl*l/V=pl^2/V
increase in resistance=9.9*10^-6*((8*0.251)^2-(8*0.025)^2)/(9*10^-8*8*2.5*10-6)
or just work out final and initial restance and subtract

Title: Re: Edexcel unit 2 physics help!!!!
Post by: Igcseboy on April 25, 2010, 10:09:22 am

thanks

another please question 19 b Jan 2010

Title: Re: Edexcel unit 2 physics help!!!!
Post by: astarmathsandphysics on April 25, 2010, 10:24:11 am

Which paper?

Title: Re: Edexcel unit 2 physics help!!!!
Post by: astarmathsandphysics on April 25, 2010, 10:30:50 am

this?

Title: Re: Edexcel unit 2 physics help!!!!
Post by: Igcseboy on April 25, 2010, 10:37:46 am

unit 1
sorry

Title: Re: Edexcel unit 2 physics help!!!!
Post by: astarmathsandphysics on April 25, 2010, 11:07:58 am

Does not obey hokes law cos not a striaght line.
Area under graph =energy and area <0.8
just count whole square part of which is below the graph, with each square being E=Fd=2*0.01=0.02J

Title: Re: Edexcel unit 2 physics help!!!!
Post by: Igcseboy on April 25, 2010, 12:03:13 pm

Quote from: astarmathsandphysics on April 25, 2010, 11:07:58 am

Does not obey hokes law cos not a striaght line.
Area under graph =energy and area <0.8
just count whole square part of which is below the graph, with each square being E=Fd=2*0.01=0.02J

how to count and get te final answer :S:S
i did not quite understand!!!

Title: Re: Edexcel unit 2 physics help!!!!
Post by: T.Q on April 25, 2010, 05:37:11 pm

Quote from: Igcseboy on April 25, 2010, 12:03:13 pm

how to count and get te final answer :S:S
i did not quite understand!!!

note : u have to convert the extension from cm to m

elastic strain energy = 1/2 x force x extension
                            = 0.5 x 12 x  0.1
                            = 0.6 J


this answer is approximation , because its a curve