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Math Help - several calculus problems from homework assignment that i couldn't solve

  1. #1
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    several calculus problems from homework assignment that i couldn't solve

    1. A particle moves on a line according to the law s=f(t) so that its velocity v=ks, where k is a nonzero constant. Its acceleration is
    (A) vk^2
    (B) sk^2
    (C) k
    (D) 0
    (E) none of these

    2. As the tides change, the water-level in a bay varies sinusoidally. At high tide today at 8 A.M., the water-level was 15 feet; at low tide, 6 hours later at 2 P.M., it was 3 feet. How fast , in ft per hr, was the water-level dropping at noon today?
    (A) 3
    (B) (π√ 3)/2
    (C) 3√ 3
    (D) π√ 3
    (E) 6√ 3

    if you could answer any of these question, help me please
    Last edited by Ackbeet; April 29th 2011 at 03:19 AM. Reason: Too many questions in one thread.
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  2. #2
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    I Like option c) or d) for the first one. But why?
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  3. #3
    MHF Contributor alexmahone's Avatar
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    Quote Originally Posted by pickslides View Post
    I Like option c) or d) for the first one. But why?
    a=\frac{dv}{dt}=k\frac{ds}{dt}=kv=k\times ks=sk^2

    Tha answer is (b).
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