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Math Help - Normal Forces

  1. #1
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    Normal Forces

    While driving along a country lane with a constant speed of 17.0 m/s, you encounter a dip in the road. The dip can be approximated as a circular arc, with a radius of 65.0m. What is the normal force exerted by a car seat on a 80.0kg passenger when the car is at the bottom of the dip.

    Do you have to do 2 equations here?? 1 will be centripetal force. Fc=mv^2/r?
    The other v=d/t???
    I am not quite sure on that one.
    Any help to get me started would be great. Or do I have it wrong?
    THanks again
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  2. #2
    A Plied Mathematician
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    Yes, you'll have centripetal force, but you'll also have gravity (pushes the passenger into the seat; hence, by Newton's 3rd law, the seat pushes back into the passenger). Just add them up to get the total.
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  3. #3
    MHF Contributor Unknown008's Avatar
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    The normal force provides the centripetal force.

    So, find F_c = \dfrac{80(17^2)}{65} = 355.7 N

    This is the resultant force. Hence the normal force = Resultant force - Weight = 355.7 - (-80g)
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  4. #4
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    Ok so I find F=ma which is 80kg X 9.8 m/s.s gives me 784 added to 355 I get 1140 N correct??
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  5. #5
    A Plied Mathematician
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    Close enough, I think.
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  6. #6
    MHF Contributor Unknown008's Avatar
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    This is what I got
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