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    (Original post by philo-jitsu)
    It said magnitude of velocity unfortunately
    so does that mean that velocity can't be negative even though it is travelling in the opposite direction?
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    Trying to put ms together...how far did the brick travel before stopping...was it 5m?
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    (Original post by mbh16)
    so does that mean that velocity can't be negative even though it is travelling in the opposite direction?
    Yeah, negative would imply a direction....speed can't be negative
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    (Original post by Simple Harmonic)
    You calculated the work done against friction in a previous question. Energy is always conserved and this energy is stored as elastic potential energy when the string is compressed.

    E = 0.5 F L

    Rearrange for F. That's what I did anyway.
    If you rearrange wouldn't you just end up with the F you put into the equation when calculating energy stored?


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    (Original post by philo-jitsu)
    Yeah, negative would imply a direction....speed can't be negative
    omg thats annoying, i even remember there wasn't much room under the x axis but i just fit it in anyway
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    It said "Magnitude" so it was only the size of the velocity and you didn't need take into account the direction
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    (Original post by philo-jitsu)
    Trying to put ms together...how far did the brick travel before stopping...was it 5m?
    1.2 metres i think mate
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    (Original post by philo-jitsu)
    Does someone know how much the diamond question where you had to draw the lines was....I skipped it due to time ? Just wondering how many marks were lost with that
    The Ray went through TIR on first instance and then its left the diamond at next boundary
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    not to offend those that didnt do as well but i think i did okay , i was a little rushed for time but i completed everything . the questions i got incorrect was the last 2 on the spring (4 marks dropped) , the violet light as i put red (not sure how many marks) i also put that the terminal speed of the empty lorry would be greater than the water lorry ...( 2 marks lost) ermmmmm.... and i also think i got the definition of center of mass a little off so maybe an extra mark .
    i think the speed optic cable might be a little off too but im not sure as people havnt said much about that one on here . i did it using c/lambda equals a constant but i know ill be wrong . maybe 59 or 60 / 70 ? can anyone advise ?
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    (Original post by jamestordoff)
    not to offend those that didnt do as well but i think i did okay , i was a little rushed for time but i completed everything . the questions i got incorrect was the last 2 on the spring (4 marks dropped) , the violet light as i put red (not sure how many marks) i also put that the terminal speed of the empty lorry would be greater than the water lorry ...( 2 marks lost) ermmmmm.... and i also think i got the definition of center of mass a little off so maybe an extra mark .
    i think the speed optic cable might be a little off too but im not sure as people havnt said much about that one on here . i did it using c/lambda equals a constant but i know ill be wrong . maybe 59 or 60 / 70 ? can anyone advise ?
    I also didn't find it in the most part too bad but I did feel very time pressured. The speed of the light in the optical fibre was just a ratio
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    what did everyone do to find the wavelength of the radiation before it entered the core? cause frequency I'm sure stays the same so i did Cs/LAMBAs = C/lamba where Cs and LAMBDA s is the values in the substance so in the core and then worked out the wavelength outside of the core(or was it asking for wavelength in the core) cant remember
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    (Original post by jamestordoff)
    not to offend those that didnt do as well but i think i did okay , i was a little rushed for time but i completed everything . the questions i got incorrect was the last 2 on the spring (4 marks dropped) , the violet light as i put red (not sure how many marks) i also put that the terminal speed of the empty lorry would be greater than the water lorry ...( 2 marks lost) ermmmmm.... and i also think i got the definition of center of mass a little off so maybe an extra mark .
    i think the speed optic cable might be a little off too but im not sure as people havnt said much about that one on here . i did it using c/lambda equals a constant but i know ill be wrong . maybe 59 or 60 / 70 ? can anyone advise ?
    When you worked out the speed of light in the substance, you use: n=c/c(substance) and for the wavelength in the material I used n=lambda/lambda(substance). I think you had the right idea though
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    (Original post by Selborn)
    I also didn't find it in the most part too bad but I did feel very time pressured. The speed of the light in the optical fibre was just a ratio
    aah right yeah , did you use the speed of light divided by the wavelength . then times by the new wavelength ? or is it the otherway round? what did we get given?
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    (Original post by txnilxnur)
    what did everyone do to find the wavelength of the radiation before it entered the core? cause frequency I'm sure stays the same so i did Cs/LAMBAs = C/lamba where Cs and LAMBDA s is the values in the substance so in the core and then worked out the wavelength outside of the core(or was it asking for wavelength in the core) cant remember
    That sounds right to me - but I used n=lamda/lambda(substance)
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    (Original post by txnilxnur)
    what did everyone do to find the wavelength of the radiation before it entered the core? cause frequency I'm sure stays the same so i did Cs/LAMBAs = C/lamba where Cs and LAMBDA s is the values in the substance so in the core and then worked out the wavelength outside of the core(or was it asking for wavelength in the core) cant remember
    i know what you mean , i cant remember what we were given and what we had to work out . i treated the frequency like a constant like yourself
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    (Original post by thatcooldude2.0)
    I did it the other way round but I see where you got that from. I calculated the force needed to decelerate it to its safe speed then it was less than 360( I think it was) so the engine will manage to decelerate it to its safe speed. Do you think that'll count too? I only realised I could've done it the other way round when the exam finished
    I'm not sure because it already said that the resultant force upwards was like 670N so I don't know what force you were working out there.. you might get marks though for saying it would land safely
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    (Original post by Rahmada)
    It must be either red or violet because they are at either end of the visible spectrum. I just don't have a clue which.
    yeah its violet because it has the smallest wavelength and i just worked out that it gave the smallest angle
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    (Original post by jamestordoff)
    1.2 metres i think mate
    It was cheers...

    So the spring question had find velocity given we know energy....then find frictional force....and then find elastic potential?

    Anything missing?
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    (Original post by jamestordoff)
    aah right yeah , did you use the speed of light divided by the wavelength . then times by the new wavelength ? or is it the otherway round? what did we get given?
    we got given refractive index an you needed to use n=C/Cs I believe
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    (Original post by jamestordoff)
    i know what you mean , i cant remember what we were given and what we had to work out . i treated the frequency like a constant like yourself
    Yeah frequency doesn't change when entering a different medium
 
 
 
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