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    (Original post by AlexeiLipov)
    For sketching graph I got this
    **** sake. I had KEmax as 80mj. So that means my second part of the answer is wrong too. How many marks would I lose for that?
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    (Original post by rm761)
    lol same, seems impossible tho
    Our galaxy weighs ~1x10^43, so that would be a VERY heavy star :P
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    (Original post by Zonothene)
    As its a binary system you have to use this if you wish to do it using kepler's 3rd law (i.e adding the two masses together in the equation).
    So I'm ****ed.
    Great. Goodbye 100% ums. ****ing ********
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    (Original post by victoria98)
    Screwed up the KE graph..., thought the maximum was 80mJ. Such a silly error... It was two marks though, what would the other mark be for? Also will there be ecf for maximum speed with 80mJ, or will they only give ecf for the time period?
    So the max was 50mj right?
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    (Original post by Pyslocke)
    **** sake. I had KEmax as 80mj. So that means my second part of the answer is wrong too. How many marks would I lose for that?
    I can't remember how many marks the graph sketching was, I think 1 mark. So you only lost 1 mark because the other parts of the question you will get error carried forward.
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    (Original post by rm761)
    lol same, seems impossible tho
    It's a star. The sun is 1x10^30. Binary stars are usually massive.
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    (Original post by Asiimov)
    I think most are saying 5/4pi, I think you might have miscounted
    i got 5/8PI as the phase difference, would 5/4PI mean its out of phase by 1/4PI???
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    Okay, so for the question about Mars' moons. What did everyone write for the speed of the moon? It said EXPECT to see so I said you would expect it to decrease in speed because the mean gravitational field acting on the moon decreases? Assuming their masses affect each other. But seriously... wtf
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    For S2 mass could i do this:

    F = GM1M2/r1^2 = M1v1^2/r1 which M1 cancels
    GM2/r1^2 = v1^2/r1
    Rearrange for M2.

    I'm not sure what answer i got but is that a correct method?
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    DIFFICULTY POLL:
    http://www.thestudentroom.co.uk/show....php?t=4176590

    votevotevote
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    (Original post by President J)
    It's a star. The sun is 1x10^30. Binary stars are usually massive.
    thats why i didnt think the 41 was too weird, i thought s2 must be so big that s1 revolves around it like the earth does around the sun fgs, then i googled mass of largest star ffs
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    same
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    I got 10^33 as the mass of star 2. Is this right?
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    (Original post by Smeagul)
    I got 10^33 as the mass of star 2. Is this right?
    that is the correct power yes
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    There goes my A

    Go to hell G484.
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    for the fireman question, i did 92g - 8.3gsin55 :/ is this correct?
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    (Original post by neyjunior)
    for the fireman question, i did 92g - 8.3gsin55 :/ is this correct?
    Had to be plus. Hose would push you back.
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    (Original post by neyjunior)
    for the fireman question, i did 92g - 8.3gsin55 :/ is this correct?
    No, the vertical component of the contact force is equal to the weight of the fireman plus the vertical component of the impulse of the water. Answer = 92g + 8.25*(whatever the speed of the water was)*sin(55)
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    (Original post by President J)
    Had to be plus. Hose would push you back.
    how many marks do you think i'll lose for that?
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    (Original post by Zonothene)
    No, the vertical component of the contact force is equal to the weight of the fireman plus the vertical component of the impulse of the water. Answer = 92g + 8.25*(whatever the speed of the water was)*sin(55)
    how many marks do you think i'll lose?
 
 
 
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