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

1. (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 ?
2. (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
3. (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?
4. (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.
5. Got 1.97 x 10^10 for young modulus
I used 5.5N and 0.008m

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6. (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
7. 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 ?
8. 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
9. (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
10. (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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11. (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/thread...e-rule.610200/ check for yourself
(Original post by Luj99)
I just drew a straight line of best fit
13. what about the one for the burns? Did we have to describe about the nodes, anti nodes and the change of phase?
14. (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
15. (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?
The burns occurred at the antinodes so distance between adjacent antinodes is half lamda. Therefore twice d is lamda.

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16. 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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17. (Original post by Chapers64)
No that's the minimum division, the absolute uncertainty is half the minimum division, https://www.physicsforums.com/thread...e-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.
18. (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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19. (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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20. 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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