# First Area Moment and Centroidal Co-ordinates

1.Homework Statement
There is a quarter circle.The centre of the circle of which the quarter circle is a part,is at the origin (0,0).Find the centroidal co-ordinates for the quarter circle.The equation of the circle for which the quarter circle is a part,is x2 +y2 = R2. where R is radius.

2.Relevant equations
M(y)= integral of (x dA), where dA is an elemental area at a distance x from Y axis.M(y) is first moment of inertia about y axis. X(c)= M(y)/A, where A is total area of quarter circle,and X(c) is the centroidal x co-ordinate.

3.The attempt at a solution
Well,i am in engineering first year and we have just started first area moment,centrodal co-ordinates,second area moment etc.So,i tried my best to understand the concepts.I did one where there is a rectangle with height h and base b.Thats easy.If we first choose a vertical strip of elementary area dA and width dx.Now,M(y)= integral of (x dA).Putting h dx in place of dA,we get an integrable equation.The limits of intigration is from 0 to b.Then,X(c)= M(y)/A.Putting the value of M(y) and A=bh,we get X(c).Similarly by choosing a horizontal strip we can get M(x),which is the first area moment about x axis.I tried to do the same for the quarter circle but I am not being able to get an integrable form.

4.Conclusion
Well,I have tried to show that I have attempted the problem and I do study.But since I'm not a genius,I need your help.Please explain the problem,because I may be a bit dumb,although I got very good marks in my school final exams.That time also,i had posted some questions on physics forums.Thanks a lot for everything...

Dick