While backing out of garage, the car abruptly and violently braked. The driver was tossed forward. The rear camera showed nothing in the car's path and no alarms had been set off. Visual review confirmed the absence of anything in the path of the automobile. The automobile was purchased new about 7-10 days before this occurrence. The driver has experienced shoulder, neck, and upper body pains somewhat responsive to acetaminophen tablets. The driver was instructed to turn off the automatic rear brake each time backing up but has not been offered a permanent fix. I do not know if Volvo has been informed or if the dealership has inspected the car.