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# AQA Physics PHYA4 - Thursday 11th June 2015 [Exam Discussion Thread] watch

1. (Original post by QueNNch)
Hey guys does anyone know how to calculate the time period for this:
January 2011

The correct answer is B but my calculations can never get that answer.
Apparently we are supposed to use ω2r = 9.81

Thanks
mg=mw²r
g=w²r
T²/4π²=r/g
T=√(4π²r/g)
2. Anybody know of any good videos for magnetic fields?
3. What are the unit for impulse and change in momentum

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4. (Original post by QueNNch)
Hey guys does anyone know how to calculate the time period for this:
January 2011

The correct answer is B but my calculations can never get that answer.
Apparently we are supposed to use ω2r = 9.81

Thanks
If objects are to appear weightless then their centripetal force is their weight, plug into formula and out pops ur answer
5. (Original post by Fvthoms)
Anybody know of any good videos for magnetic fields?
6. (Original post by fvthoms)
anybody know of any good videos for magnetic fields?
7. (Original post by QueNNch)
Hey guys does anyone know how to calculate the time period for this:
January 2011

The correct answer is B but my calculations can never get that answer.
Apparently we are supposed to use ω2r = 9.81

Thanks
just did it calc and got 1.4
9.81 divided by radius of earth
square root ans
ω= 2 pi / T
2pi / ans = T in seconds
Convert to hours
8. Cheers 👍

Edit: Vid was just what I needed. Repped.
9. (Original post by QueNNch)
Hey guys does anyone know how to calculate the time period for this:
January 2011

The correct answer is B but my calculations can never get that answer.
Apparently we are supposed to use ω2r = 9.81

Thanks
Hope this helps!
10. (Original post by C-king)
Attachment 424989
Can someone pls help me on this have no clue
BUMP
11. (Original post by gcsestuff)
What are the unit for impulse and change in momentum

Posted from TSR Mobile
Impulse=∆momentum=kgms-1=Ns
12. (Original post by JaySP)
mg=mw²r
g=w²r
T²/4π²=r/g
T=√(4π²r/g)
Cheers.
13. (Original post by QueNNch)
Hey guys does anyone know how to calculate the time period for this:
January 2011

The correct answer is B but my calculations can never get that answer.
Apparently we are supposed to use ω2r = 9.81

Thanks
mw^2r = GMm/r^2

rearranges to

w = (GM/r^3)^1/2

You get the answer in seconds, so divide it by 3600 and it should be 1.4 hours.

Make sure you cube the radius
14. (Original post by Dante991)
yeah me too, 19 was just like what
Tbh I'm like that with most of these mc questions and it's not good when we're just over 12 hours away from the exam!
Could you help me with 20 and 21 please if you got them? Thanks.
15. Anyone mind explaining Q15 of multiple choice 2014?
Tbh I'm like that with most of these mc questions and it's not good when we're just over 12 hours away from the exam!
Could you help me with 20 and 21 please if you got them? Thanks.

Which paper are those questions from?
17. (Original post by frankiejayx)
Anyone mind explaining Q15 of multiple choice 2014?
Post a link to the question pls
Tbh I'm like that with most of these mc questions and it's not good when we're just over 12 hours away from the exam!
Could you help me with 20 and 21 please if you got them? Thanks.
I'm looking for someone to show me how to do them too, absoulte killer paper
19. (Original post by DanielWall96)
Post a link to the question pls
http://filestore.aqa.org.uk/subjects...1-QP-JUN14.PDF
20. (Original post by Dante991)
I'm looking for someone to show me how to do them too, absoulte killer paper
I'll try help link me the questions

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