An object is made of glass and has the shape of a cube 0.11m on a side, according to an observer at rest relative to it. However, an observer moving at high speed parallel to one of the object's edges and knowing that the object's mass is 3.2kg determines its density to be 7800kg/m3, which is much greater than the density of glass. What is the moving observer's speed (in units of c) relative to the cube?