A small square plank of oak floats in a beaker half full of water. The piece of oak is 7 cm on a side and 3 cm thick and floats on its side as shown in Figure P10.80. Density of oak 750kg/m^3 Density of water 1000kg/m^3 There were two parts to the problem, the first is: Find the location of the center of mass of the plank with respect to the water’s surface. Someone else gave me the equation, so I was able to get this part, but I can't find the equation myself anywhere. s=side length in meters w=width in meters ?(oak)=750 ?(water)=1000 center mass= w-[(s^2)*w*750/(1000*(s^2))] Second part (I need help here) is: A very light vegetable oil is poured slowly into the beaker, so that the oil floats on the water without mixing and until the oak plank is a few centimeters below the surface of the oil. If the density of the oil is 640 kg/m3, calculate the new position of the center of mass of the plank with respect to the water’s surface. For the first part, I got .0075m. As I stated, someone just gave me the equation so I got the answer, but it didn't help me with understanding how to solve the problem. So I am completely lost and if anyone could just point me in the right direction, it would be appreciated.