A wooden block with mass 1.50 kg is placed against a compressed spring at the bottom of an incline of slope 30.00 (point A). When the spring is released, it projects the block up the incline. At point B, a distance of 6.00 m up the incline from A, the block is moving up the incline at 7.00 m/s and is no longer in contact with the spring. The coefficient of kinetic friction between the block and the incline is μk = 0.50. The mass of the spring is negligible. Calculate the amount of potential energy that was initially stored in the spring.