Three uniform spheres are located at the corners of an equilateral triangle. Each side of the triangle has a length of 1.2 m. Two of the spheres has a mass of 2.80 kg each. The third sphere (mass unknown) is released from the rest. Considering only the gravitational forces that the spheres exert on each other, what is the magnitude of the initial acceleration of the third sphere?

Use \Sigma \vec F=m \vec a, with \Sigma \vec F =sum of gravitational forces between the third sphere and the first two. Post your attempt here and we'll check it for you.