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Math Help - Physics problem.

  1. #1
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    Physics problem.

    1 ) A vacum cleaner is pulled with a force of 40 N making an angle of 25 with the floor . If it is dispaced along the floor through 3 m , calculate the work done on i .

    2 ) A car of mass 1500 kg being towed has a net foward force of 4500 N applied to i . The car starts from rest and travels down a horizontal highway . Find the speed of the car after it has travelled 200 m .


    ny answer >

    1)

    w = FocQ Dx

    =40cos25

    =108.7 J



    2 )



    pe = pe = w = 1/2mv^2

    1/2mv^2 = fcos180 200

    v^2 = -1200

    v = 34.6

    speed =

    34. 4
    Last edited by mr fantastic; November 18th 2010 at 12:07 PM. Reason: Title.
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  2. #2
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    Quote Originally Posted by r-soy View Post
    1 ) A vacum cleaner is pulled with a force of 40 N making an angle of 25 with the floor . If it is dispaced along the floor through 3 m , calculate the work done on i .

    2 ) A car of mass 1500 kg being towed has a net foward force of 4500 N applied to i . The car starts from rest and travels down a horizontal highway . Find the speed of the car after it has travelled 200 m .

    ny answer >

    1)

    w = FocQ Dx

    =40cos25
    =108.7 J



    2 )



    pe = pe = w = 1/2mv^2

    1/2mv^2 = fcos180 200

    v^2 = -1200

    v = 34.6

    speed =

    34. 4
    Dear r-soy,

    The answer of the first one is correct, although the highlighted step is incorrect (probably a typo). It should be 3\times40\times\cos25^o

    The second problem was done in an incorrect manner. Please check the highlighted part. If I give you a hint, the car is travelling to the direction of the applied force; not in the opposite direction.
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  3. #3
    MHF Contributor Unknown008's Avatar
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    The fact that you got

    v^2 = -1200

    r-soy, you should have guessed that something was wrong.

    And the last answer is not 34.4 m/s, but 34.6 m/s, I'll assume that you did a typo...
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  4. #4
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    yes, about second
    i got 34.6

    ?
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