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Applications of vector algebra to physics

  1. Jul 29, 2009 #1
    1. The problem statement, all variables and given/known data

    A ball of mass 1 kg is acted upon by three forces:
    Fl = (2i + 4j - 3k) N, F2 = (-3i - j + 2k) Nand F3 = (i - 5j - k) N.
    Determine a vector expression for the acceleration of the particle.
    If, at time t = 0, it has position r = (i +j) m and velocity u = (i +3j)m/s, write
    down the position vector of the ball at time t. Hence, determine its position and
    velocity after 2 seconds.


    2. Relevant equations



    3. The attempt at a solution

    resultant force & acceleration due to forces:

    Fresultant = F1+F2+F3 = -(2j+2k)N

    F=ma, m=1kg, therefore a = -(2j+2k)ms-2


    position vector at (t), and velocity and position at t=2:

    r(t)=r(0)+ut+[tex]\frac{1}{2}[/tex]at2

    therefore r(t)=(i+j)+(i+3j)-[tex]\frac{1}{2}[/tex](j+k)t2

    so at t=2,

    r(2)=(3i+5j-2k), and v(2)=(i+j-2k)ms-1


    any problems? thanks for all the help always!
     
  2. jcsd
  3. Jul 29, 2009 #2

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    No conceptual problems. You are being pretty sloppy about putting the numbers into r(t)=r(0)+v(0)*t+(1/2)*a*t^2, though. I'd try that part again.
     
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