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Edexcel IAL Physics Unit 03 WPH03 - 10th of May, 2017

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Reply 60
Original post by inshaa
was it supposed to be 1.91 x 10^10 ???


I'm not too sure I got 1.99X10^8 and what was the shape of the force against extension graph ?
Original post by Luj99
I think I did and how did your force against extension graph look like ?
Passed limit of proportionality at 5.9N and then started curving I think
Reply 62
Original post by Chapers64
Passed limit of proportionality at 5.9N and then started curving I think


But they asked to draw a line of best fit so how can it curve?
Original post by Luj99
But they asked to draw a line of best fit so how can it curve?


A line of best fit goes through all the points.. So in this case it has to be a curve.
(edited 6 years ago)
Got 1.97 x 10^10 for young modulus
I used 5.5N and 0.008m


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Original post by Chapers64
Uncertainty on metre rule is +/- 0.5mm, 0.5/60 = 0.83%

You're wrong the uncertainty on a meter rule is +/- 1mm
Reply 66
i think till 6N it obeyed Hookes law then it lost its elastic behaviour...plastic deformation began so mine was a a curve.. what about yours?
Original post by Luj99
I'm not too sure I got 1.99X10^8 and what was the shape of the force against extension graph ?
Reply 67
yeah mine too was a curve from 5.9-6.0 N
Original post by Chapers64
Passed limit of proportionality at 5.9N and then started curving I think
Reply 68
Original post by inshaa
i think till 6N it obeyed Hookes law then it lost its elastic behaviour...plastic deformation began so mine was a a curve.. what about yours?


I just drew a straight line of best fit
Original post by mandax_25
You're wrong the uncertainty on a meter rule is +/- 1mm


Was it okay to round it off to 2%


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Original post by mandax_25
You're wrong the uncertainty on a meter rule is +/- 1mm
No that's the minimum division, the absolute uncertainty is half the minimum division, https://www.physicsforums.com/threads/what-is-the-uncertainty-in-a-metre-rule.610200/ check for yourself
Reply 71
and what about your percentage uncertanity ? was it 1.7%
Original post by Luj99
I just drew a straight line of best fit
Reply 72
what about the one for the burns? Did we have to describe about the nodes, anti nodes and the change of phase?:confused::confused:
Original post by zenab_k
For the percentage uncertainty weren't we supposed to change 0.01mm into cm then divide it by 6 and multiply it by 100?

If you used vernier calliper as your measuring tool, that's correct
Original post by inshaa
what about the one for the burns? Did we have to describe about the nodes, anti nodes and the change of phase?:confused::confused:


The burns occurred at the antinodes so distance between adjacent antinodes is half lamda. Therefore twice d is lamda.


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Reply 75
:frown: i lost my 2 marks there... i talked about the wave being hit on a barrier so it traveled a distance L a the reflected wave travels back giving a total distance of 2L
Original post by Droneon
The burns occurred at the antinodes so distance between adjacent antinodes is half lamda. Therefore twice d is lamda.


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Original post by Chapers64
No that's the minimum division, the absolute uncertainty is half the minimum division, https://www.physicsforums.com/threads/what-is-the-uncertainty-in-a-metre-rule.610200/ check for yourself

Yeh I guess you're right... You can take the uncertainty as either +/- 0.5mm or 1mm.
You'll get marks either way.
Original post by mandax_25
Yeh I guess you're right... You can take the uncertainty as either +/- 0.5mm or 1mm.
You'll get marks either way.


Is it okay if I rounded off the % uncertainty to 2% instead of 1.7%?


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Original post by Droneon
Is it okay if I rounded off the % uncertainty to 2% instead of 1.7%?


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Anyone??


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I kept my percentage uncertainty as 1.67% i didnt round it off to 1.7% i would still get the mark right?

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