Hey there! Sign in to join this conversationNew here? Join for free
    Offline

    3
    ReputationRep:
    (Original post by particlestudent)
    How many marks was the derivation for Venus and then working it's R out
    2 and 3 I think
    Offline

    1
    ReputationRep:
    (Original post by Euclidean)
    Nope. Because V is a magnitude.

    0 = mv - NV

    So:

    NV = mv

    V = mv/N

    Posted from TSR Mobile
    old momentum = 0
    new momentum = 0
    VN+mv=0
    because the value of v and V already account for the different directions.
    but the mark scheme will probably not care
    V is not a magnitude, it said Velocity V
    Offline

    1
    ReputationRep:
    (Original post by johnapplebottom)
    no wat, 220 was the nuclean number before it decayed by alpha particle thing
    so after it was 220-4 = 216
    Yup
    Offline

    0
    ReputationRep:
    (Original post by duncant)
    what did people say about the B- emission any why the equations wouldnt work? I said that B emission is an electron which isnt a nucleon, which is what the equations represent?
    Mass isn't conserved - neutron turns into proton emitting B-
    Offline

    10
    ReputationRep:
    (Original post by IMZL)
    120 UMS boundary predictions?
    I recon 66?
    Offline

    12
    ReputationRep:
    (Original post by IMZL)
    120 UMS boundary predictions?
    62/75 - higher than last year, but multiple choice was hard and there were a lot of wordy questions.
    Offline

    15
    ReputationRep:
    I got about 45? Will i get at least 80 Ums marks?
    Offline

    1
    ReputationRep:
    do you get a mark for saying electricity can be generated from the brakes to power the car to reduce fuel consumption and for disadvantage that in emergency situations the brakes may not slow down quick enough
    Offline

    1
    ReputationRep:
    Annoyingly, was going to say the x-axis was the time period squared to give a straight gradient based on the equation but bottled it. Also, I said Emf induced is *proportional* to the rate of change magnetic flux as opposed to *directly proportional*, are we thinking I'll lose the marks on that one?
    Offline

    10
    ReputationRep:
    (Original post by thestudntrm)
    Mass isn't conserved - neutron turns into proton emitting B-
    How is it not conserved? The proton is less massive than the neutron. Don't forget an antineutrino is produced which takes momentum (and hence energy) from the decay away, so the equations won't work; it's a three body process.
    Offline

    1
    ReputationRep:
    (Original post by particlestudent)
    How many marks was the derivation for Venus and then working it's R out
    I think it was 4 for the proof then 2 for calculating R.
    Offline

    9
    ReputationRep:
    (Original post by Blackmagic123)
    old momentum = 0
    new momentum = 0
    VN+mv=0
    because the value of v and V already account for the different directions.
    but the mark scheme will probably not care
    V is not a magnitude, it said Velocity V
    It did say velocity I agree, BUT the arrows were in opposite directions!
    Offline

    1
    ReputationRep:
    (Original post by EdwinLangley)
    I did the exact same thing unfortunately - noticed my mistake coming out.

    You get that time constant if you took Q/Q0 to be 0.8 rather than 0.2...

    Sorry - hope we didn't lose many marks for it and get ECF for the resistance
    I did the same but then got a stupidly large time constant of like 88000 so knew it was wrong.
    Offline

    1
    ReputationRep:
    (Original post by IMZL)
    It's in the opposite direction so mv-NV=0 but that means V=mv/N not -mv/N.
    Yes and I got the derivation correct using the positive version so it must be correct
    Offline

    10
    ReputationRep:
    (Original post by Jordenwilder1998)
    do you get a mark for saying electricity can be generated from the brakes to power the car to reduce fuel consumption and for disadvantage that in emergency situations the brakes may not slow down quick enough
    I put the same for the advantage. Pretty sure that electromagnetic braking is faster than regular braking . . .
    Offline

    3
    ReputationRep:
    Say 66 was 120 UMS boundary, would there be any advantage in getting over 66 in terms of how well you'd need to do in unit 5?
    Offline

    2
    ReputationRep:
    (Original post by ombtom)
    Back to the V = ±mv/N thing...

    V and v are velocities.

    The velocities are in different directions, as shown by the arrows in the diagram.

    Since they are in different directions, V must equal -mv/N.

    SOMEONE HELP. :lol:
    momentum before is 0

    mv-MV=0
    mv=MV
    V=mv/M
    Offline

    9
    ReputationRep:
    (Original post by wallpaperpaste)
    Yes and I got the derivation correct using the positive version so it must be correct
    Positive version is correct but you would still get correct derivation with negative.
    Offline

    3
    ReputationRep:
    (Original post by wallpaperpaste)
    Yes and I got the derivation correct using the positive version so it must be correct
    Likewise
    Offline

    3
    ReputationRep:
    (Original post by IMZL)
    Say 66 was 120 UMS boundary, would there be any advantage in getting over 66 in terms of how well you'd need to do in unit 5?
    No, once you reach the 120 UMS boundary then you can get no more UMS from that paper.
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    Would you like to hibernate through the winter months?
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • 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.