ON MONDAY MAY 12 I WAS INVOLVED IN A CAR ACCIDENT. I AM CONCERNED BECAUSE MY AIR BAD DID NOT ACTIVATE. I WAS DRIVING A 2001 FORD F250, GOING AROUND 40-45 MILES PER HOUR. I RAN INTO THE BACK OF A PERSON THAT WAS SITTING STOPPED AT A RED LIGHT. I NEVER HIT MY BRAKES SO I HIT HER STRAIGHT IN THE REAR. WHY TYPE OF IMPACT DOES IT TAKE FOR THE SENSOR TO GO OFF FOR AIR BAGS? *NLM