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Applied maths statics question

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  • 02-09-2009 6:49pm
    #1
    Closed Accounts Posts: 175 ✭✭


    this question is from fundamental applied mathematics Oliver Murphy
    page 205 Q5

    abc is an isoceles triangle the midpoint of [bc] is d.
    M is the midmoint of [ad].
    a circle of radius 7/2 cm and center M is cut from the triangle.
    how far from d is the center of gravity of the remainder(take pi =22/7)



    so far i have the center of gravity of the triangle and of the circle


    please help thank you soooooooooo much!


Comments

  • Registered Users Posts: 1,595 ✭✭✭MathsManiac


    You need to find the two masses as well as the two centres of gravity.

    Think about adding two masses first; subtracting follows the same idea.

    If you had a mass of 10 kg at one point and a mass of 5 kg at another point, then you want to find the point at which the two moments would cancel out. You get it by dividing the segment between them in the ratio 1:2.

    Similarly, think of the circle as having a negative mass at its cg (because you're removing it) and combine that with the mass of the triangle at its cg.

    Make sense?


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