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    I have a homework question as follows:

    A and B are two points in a vertical line with B a distance of 4m above A. A body P, of mass m kg is projected vertically upwards from A with a speed of 10 m/s.

    Find:
    a) The speed of P when it passes upwards through B

    I used GPE and KE before and after to get:
    100m = 8 + mv^2

    However, the expected answer for v is not in terms of m. Can anyone help?

    Many thanks in advance
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    v2 = u2 + 2as


    u = 10

    a = -9.8

    s = 4
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    (Original post by the bear)
    v2 = u2 + 2as


    u = 10

    a = -9.8

    s = 4
    So for that bit you just use normal suvat?
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    (Original post by bendent1234)
    So for that bit you just use normal suvat?
    indeed
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    You can perfectly well use KE and GPE too. In fact you very nearly did it. It should have come out as 100m = 8m + mv^2, then you can cancel m for all terms, and hey presto you have the same thing as produced via the SUVAT route. (It looks as though your GPE somehow became 4g rather than 4mg).
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    (Original post by old_engineer)
    You can perfectly well use KE and GPE too. In fact you very nearly did it. It should have come out as 100m = 8m + mv^2, then you can cancel m for all terms, and hey presto you have the same thing as produced via the SUVAT route. (It looks as though your GPE somehow became 4g rather than 4mg).
    Oh of course, that was a careless error! Thanks
 
 
 
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