Join TSR now and get all your revision questions answeredSign up now

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

    Offline

    3
    ReputationRep:
    june 13 section a
    Question 23
    arent b and c also correct as well?
    Offline

    12
    ReputationRep:
    Guys make sure to check out the units PA10 from the old spec there are quite a few relevant questions in there you can find them on egsphysics
    Offline

    1
    ReputationRep:
    (Original post by oonic0rn)
    http://filestore.aqa.org.uk/subjects...1-QP-JAN13.PDF for question 22 i have no idea how to work out the frequency?
    By observation, if you compare e=20sin(100pit), to e=BANsin(wt), wt=100pit so w=100pi.

    w=2pi/T , so Time period = 1/50 . Freq=1/T , so freq=50Hz.
    Offline

    2
    ReputationRep:
    http://filestore.aqa.org.uk/subjects...1-QP-JUN14.PDF

    Can someone please help me with questions 4,6,8,13 from june 14 paper thanks.
    Offline

    3
    ReputationRep:
    I have two ques:
    1) Would you get any marks if you did two distinct working out for one question and one working out was correct although in the answer place you wrote the wrong answer?

    2) What if you get a ques wrong like say example with the parcel on the floor van; if you get the equation wrong all the other parts would be affect would ecf still be valid or?
    Offline

    2
    ReputationRep:
    (Original post by saad97)
    http://filestore.aqa.org.uk/subjects...2-QP-JUN14.PDF

    Can someone please help me with questions 4,6,8,13 from june 14 paper thanks.

    Ohh
    Wrong link

    Posted from TSR Mobile
    Offline

    2
    ReputationRep:
    Name:  ImageUploadedByStudent Room1433959187.476419.jpg
Views: 219
Size:  105.1 KB

    Found this on the last past paper I was going to do. Is it a sign?????


    Posted from TSR Mobile
    Offline

    2
    ReputationRep:
    (Original post by Kingnig)
    Does anyone has a list of past grade boundaries?
    on the first page
    Offline

    15
    ReputationRep:
    (Original post by saad97)
    http://filestore.aqa.org.uk/subjects...2-QP-JUN14.PDF

    Can someone please help me with questions 4,6,8,13 from june 14 paper thanks.
    4) a full circle is 2pi, so using time = distance over speed, 2pi over pi/2 which is 4.
    So it takes 4 seconds to go around once. so 6 seconds would be one and a half times so it will be directly opposite P, so a diameter away.

    6) you have to make an equation. mv^2/r is equal to mg - T, something along those lines so you get B

    8) Use Vmax equation since it has 0 displacement so max speed

    13) really tough one, i didnt get this one mate
    Offline

    2
    ReputationRep:
    Name:  ImageUploadedByStudent Room1433959309.976139.jpg
Views: 121
Size:  108.7 KB


    I think it was Newton who said he wasn't sure that change of design to change natural frequency was true but it's here in the mark scheme


    Posted from TSR Mobile
    Offline

    2
    ReputationRep:
    One more from me: could anyone help me with this question? Thanks!

    Name:  Capture.PNG
Views: 182
Size:  51.5 KB
    Offline

    2
    ReputationRep:
    (Original post by a.a.k)
    Ohh
    Wrong link

    Posted from TSR Mobile
    Sorry my bad.
    Offline

    2
    ReputationRep:
    (Original post by saad97)
    Sorry my bad.
    No worries

    Posted from TSR Mobile
    Offline

    19
    ReputationRep:
    What's the best way to revise for 6 markers?

    I can look over the bridge applications
    Transformers and sending high voltage over long distances

    Also, what if the 6 marker is sneakily on momentum again
    Offline

    2
    ReputationRep:
    (Original post by aprocrastinator)
    what on earth is back emf PLEASE
    An emf that opposes the supply voltage (in the opposite direction/ pi out of phase). It opposes the supply voltage because of Lenz' law:

    In an electric motor (such as a screwdriver) the supply voltage creates a magnetic field in the coil. If the motor is spinning, it cuts through the field so a change in flux is experienced so an emf is generated in the coil. Because of Lenz' law, this emf must be in the opposite direction to the supply voltage.

    A back emf is also generated in a transformer in a similar way: mag field induced in primary, but this time an emf is generated not because the coil is moving but because the voltage alternates. The alternating voltage causes the magnetic field lines to change so the coil experiences a change in flux...
    Offline

    3
    ReputationRep:
    What are the differences and similarities between low polar orbits and geosynchronous orbits? Examples for uses of each?
    Offline

    2
    ReputationRep:
    (Original post by Dante991)
    4) a full circle is 2pi, so using time = distance over speed, 2pi over pi/2 which is 4.
    So it takes 4 seconds to go around once. so 6 seconds would be one and a half times so it will be directly opposite P, so a diameter away.

    6) you have to make an equation. mv^2/r is equal to mg - T, something along those lines so you get B

    8) Use Vmax equation since it has 0 displacement so max speed

    13) really tough one, i didnt get this one mate
    Thank you so much. The june 14 paper is incredibly difficult, I'm screwed if it's anywhere near as hard tomorrow!
    Offline

    1
    ReputationRep:
    (Original post by Dante991)
    4) a full circle is 2pi, so using time = distance over speed, 2pi over pi/2 which is 4.
    So it takes 4 seconds to go around once. so 6 seconds would be one and a half times so it will be directly opposite P, so a diameter away.

    6) you have to make an equation. mv^2/r is equal to mg - T, something along those lines so you get B

    8) Use Vmax equation since it has 0 displacement so max speed

    13) really tough one, i didnt get this one mate
    For 13, you have to equate F and 0.5F for their respective distances.

    0.5(QQ/4pi x eo x d ) = QQ/4pi x eo x 20x10-3

    All constants cancel, both the charges cancel.
    Offline

    15
    ReputationRep:
    (Original post by saad97)
    Thank you so much. The june 14 paper is incredibly difficult, I'm screwed if it's anywhere near as hard tomorrow!
    Could'nt agree with you more man, way harder than past papers so fingers crossed
    Offline

    15
    ReputationRep:
    (Original post by Deddy)
    For 13, you have to equate F and 0.5F for their respective distances.

    0.5(QQ/4pi x eo x d ) = QQ/4pi x eo x 20x10-3

    All constants cancel, both the charges cancel.
    Thanks man, I had the right idea but the maths kinda confused me so I couldnt work it out, I hate those sort of questions sometimes
 
 
 
Poll
Which pet is the best?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Quick reply
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.