Edexcel unit 2 physics help!!!!

[Igcseboy]

Question 21 c (ii)

june 2009 unit 2

helpp urgentsss

[astarmathsandphysics]

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

[Igcseboy]

thanks

another please question 19 b Jan 2010

[astarmathsandphysics]

Which paper?

[astarmathsandphysics]

this?

[Igcseboy]

unit 1
sorry

[astarmathsandphysics]

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

[Igcseboy]

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!!!

[T.Q]

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