WHILE DRIVING AT A RATE OF APPROX. 35 MILE PER HOUR THE BRAKES WENT DOWN TO THE FLOOR WHICH RESULTED IN A BACK END COLLISON . THE PASSENGER SEAT BELT AND THE AIR BAGS DID BOT WORK. ACCIDENT WAS REPOTED TO POLICE AND INSURANCE COMPANY. INSPECTOR STATED THAT THE SEATBELT AND AIRBAG WAS OK. THE CAR IS AT THE DEALERSHIP HAVING AMASTER CYLINDERREPALCED, FROZEN CALIPERS REPLACED AND BRAKE PADS REPLACED BECAUSE OF UNEVEN WEAR.