EMPLOYEE WAS SITTING UP ON BATTERY POWERED SCOOP TRACTOR TIRE, WHEN FORKLIFT WAS PLACING BATTERY PACK ONTO SCOOP. FORKLIFT ACCIDENTALLY RAISED CORNER OF SCOOP TRACTOR, AND WHEN IT BOUNCED 8"" B ACK DOWN TO GROUND EMPLOYEE BOUNCED STRIKING TAIL BONE AGAINST SCOOP TIRE AND METAL.