I WAS ENTERING FREEWAY ON RAMP. HEAVY TRAFFIC. BEAUTIFUL DAY, DRY ROADS. VEHICLE IN FRONT OF ME MADE BRAKED SUDDENLY. I QUICKLY APPLIED MY BRAKES. MY BRAKES DID NOT ENGAGE. I WAS APPROXIMATELY 2-3 CAR LENGTHS BEHIND VEHICLE IN FRONT OF ME AND TRAVELING 25 MPH. WHEN I APPLIED BRAKES, MY CAR DID NOT EVEN TRY TO STOP, IT BASICALLY SLID 2 1/2 CAR LENGTHS INTO REAR OF VEHICLE. MY VEHICLE ONLY STOPPED MOVING BECAUSE IT WAS STOPPED BY VEHICLE IN FRONT.