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Math Help - [SOLVED] Mechanics Review Homework - Stuck =[

  1. #1
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    [SOLVED] Mechanics Review Homework - Stuck =[

    A body of mass 2kg is in equilibrium under the action of three coplanar forces, P, Q and R where P=3xi-2yj N, Q=2yi-4xj N, and R=-11i+4j N.

    a) Calculate the values of x and y.
    The force P ceases to act. Find.
    b) The resulting acceleration of the body in component form.
    c) The magnitude of the acceleration, giving your answer to 1 decimal place.

    i and j are unit vectors.

    I am completely confused by this question, can anyone offer up a method?
    Thanks!
    Last edited by Jameson; March 31st 2009 at 02:07 PM. Reason: question restored
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  2. #2
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    Quote Originally Posted by Hammeh View Post
    A body of mass 2kg is in equilibrium under the action of three coplanar forces, P, Q and R where P=3xi-2yj N, Q=2yi-4xj N, and R=-11i+4j N.

    a) Calculate the values of x and y.
    The force P ceases to act. Find.
    b) The resulting acceleration of the body in component form.
    c) The magnitude of the acceleration, giving your answer to 1 decimal place.

    i and j are unit vectors.

    I am completely confused by this question, can anyone offer up a method?
    Thanks!
    system is in equilibrium ... \sum{F_i} = 0 , \sum{F_j} = 0

    3x + 2y - 11 = 0

    -2y - 4x + 4 = 0

    solve the system for x and y


    P is taken away ... net force = Q + R

    a_i = \frac{F_i}{m} ... a_j = \frac{F_j}{m}

     <br />
|a| = \sqrt{a_i^2 + a_j^2}<br />

    do it.
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  3. #3
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    Quote Originally Posted by skeeter View Post
    system is in equilibrium ... \sum{F_i} = 0 , \sum{F_j} = 0

    3x + 2y - 11 = 0

    -2y - 4x + 4 = 0

    solve the system for x and y


    P is taken away ... net force = Q + R

    a_i = \frac{F_i}{m} ... a_j = \frac{F_j}{m}

     <br />
|a| = \sqrt{a_i^2 + a_j^2}<br />

    do it.
    And once you find a you can use pythagoras to find the magnitude
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  4. #4
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    Quote Originally Posted by e^(i*pi) View Post
    And once you find a you can use pythagoras to find the magnitude
    I thought I mentioned that ...

     <br />
|a| = \sqrt{a_i^2 + a_j^2}<br />
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    Thanks

    Thanks skeeter, excellent method!
    Thanks added to your profile

    This thread can now be closed.
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