Final answer:
The lag distance when braking at 55 mph on dry pavement is approximately 40.3 feet, which is calculated by converting the speed to feet per second and multiplying by an average reaction time of 0.5 seconds.
Step-by-step explanation:
The lag distance when braking at 55 mph on dry pavement refers to the distance a vehicle travels during the driver's reaction time, before the brakes are even applied. To calculate this distance, one would typically use the formula distance = speed x time. Assuming an average reaction time of 0.5 seconds (which is the time it takes for a driver to react and actually start braking), you'll first convert the speed from mph to feet per second (mps). One mile per hour is equivalent to 1.467 feet per second, so 55 mph would be 55 x 1.467 = 80.685 feet per second. Multiplying this speed by the reaction time gives us the lag distance: 80.685 feet/second x 0.5 seconds = 40.3425 feet. Therefore, the lag distance before braking begins is approximately 40.3 feet on dry pavement, assuming an average reaction time.