A thin wire of length L and uniformly density ρ is bent into a circular loop with center at O.The moment of inertia of it about a tangential axis lying in the plane of loop is. Ans : Mass M is not given,but ρ is given. So M=ρL3->(1) (L3 means L cube,no idea how to post it in that manner!). For a circular loop, we all know the formula for that condition is (3/2)MR square. Applying this in equation for equation (1) will give (3/2)ρL3 x (L square/4∏ square) This will give 3ρL raised to 5 / 8∏ square. But my teacher told the answer is 3ρL cube/8∏square. This is not a home work.This is just a practice for me. In this,where is my mistake?