Question

The three 500 g masses in the daigram are connected by massless, rigid rods to form a triangle. What is the triangle's rotational energy (in J) if it rotates at 1.50 rev/s about an axis through the center?

(Diagram shows equilateral triangle with 500g masses at each point, the distance from point to point is 40cm and it has three 60deg angles [equilateral])

I keep getting the same thing and it's wrong

Answer 1

energy= 1/2 I w^2

I= 3*mx^2 where cos30=x/.2meter

m= .5kg
w=1.50*2PI rad/sec

Answer 2

I do not understand the part in which you solve for x. Is it supposed to be the cos of 60 equals x divided by .2?