A catapult has two rubber bands, each rubber band has a rectangular cross-section with a width 8 mm and thickness of 2 mm. The unstretched length of the rubber band is 300 mm. When the catapult is used, its arms are stretched to three times their original length before release. Assume the elastic modulus of rubber is 10-3 GPa and that it remains constant when the rubber band is stretched. How much elastic energy is stored in the catapult just before its release? The operating equation is given as follows: U=EAx^2/2L
Where, U is the elastic energy stored in each rubber band, E is the elastic modulus, A is the area of cross section of the rubber band, x is the amount of stretch of the rubber band, and L is the unstretched length of the rubber band.