A set of crash tests consists of running a test car moving at a speed of 11.4 meters/sec (26 mph) into a solid wall. Strapped securely in an advanced seat belt system, a 59kg (130 lbs) dummy is found to move a distance of 0.66 meters from the moment the car touches the wall to the time the car is stopped. Calculate the size of the average force which acts on the dummy during that time. Where do I start? And how do I calculate average force?