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    Can someone help me understand the difference between the parts i) and ii)... I thought that the string would become slack when the EPE=0, but this would occur when length=0.5m, as in part ii)??
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    (Original post by pippabethan)
    Can someone help me understand the difference between the parts i) and ii)... I thought that the string would become slack when the EPE=0, but this would occur when length=0.5m, as in part ii)??
    AFAIK, there's a difference between springs and strings. Strings become slack when they reach their natural length, this makes intuitive sense because if you compress a string any further than its natural length, it just becomes limp and slack.

    Springs on the other hand, become "slack" when their EPE is 0.
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    (Original post by Zacken)
    AFAIK, there's a difference between springs and strings. Strings become slack when they reach their natural length, this makes intuitive sense because if you compress a string any further than its natural length, it just becomes limp and slack.

    Springs on the other hand, become "slack" when their EPE is 0.
    But wouldn't EPE=0 once the natural length had been reached for a string anyway?
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    (Original post by pippabethan)
    But wouldn't EPE=0 once the natural length had been reached for a string anyway?
    Hmm, yes - that's when extension is 0. So EPE=0 means extension =0 means length=natural length.
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    (Original post by Zacken)
    Hmm, yes - that's when extension is 0. So EPE=0 means extension =0 means length=natural length.
    So what's the difference between i) and ii)?
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    (Original post by pippabethan)
    So what's the difference between i) and ii)?
    That's really odd... does the book have a different answer for each part?

    AFAICS, it is the same and it's more of a "trick" question.
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    (Original post by Zacken)
    That's really odd... does the book have a different answer for each part?

    AFAICS, it is the same and it's more of a "trick" question.
    I thought that too, but there are two different answers. I worked it backwards, and the answer seems to correspond to the particle being 1m below P (so it's GPE having changed by 1mg) so I think maybe a misprint?
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    (Original post by pippabethan)
    I thought that too, but there are two different answers. I worked it backwards, and the answer seems to correspond to the particle being 1m below P (so it's GPE having changed by 1mg) so I think maybe a misprint?
    Yep, misprint sounds correct.
 
 
 
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