Look at the drawing given in the figure which has been drawn with ink of uniform line- thickness. The mass of ink used to draw each of the two inner circles, and each of the two line segments is m. The mass of the ink used to draw the outer cirlce is 6m. The coordinates of the centres of the different parts are :
outer cirlce (0,0)
left inner circle (-a,a)
right inner cirlce (a,a)
vertical line (0,0)
and horizontal line (0,-a)
The y-coordinates of the centre of mass of the ink in this drawing is