Final answer:
At 30 mph, it can take about 6.7 meters just to react before applying the brakes. The total stopping distance varies with reaction time and road conditions. A car initially traveling at 13.4 m/s (30 mph) with a reaction time of 0.500 seconds will cover 6.7 meters during the reaction time.
Step-by-step explanation:
At 30 mph, it can take various distances to react and bring your vehicle to a stop since the stopping distance depends on several factors, including the driver's reaction time and the road conditions. However, when considering a typical reaction time of about 0.500 seconds and a car traveling at an initial speed of 30 mph (13.4 m/s), the car travels during the driver's reaction time before any deceleration occurs.
To calculate the distance traveled during the reaction time, we can use the formula: distance = speed × time. Since the car's initial speed is 30 mph, which equates to approximately 13.4 m/s, and the driver's reaction time is assumed to be 0.500 seconds, the car covers a distance of 13.4 m/s × 0.500 s = 6.7 meters during the reaction time alone. After the reaction time, the car then begins to decelerate, and this stopping distance varies depending on whether the road is dry or wet, with a higher stopping distance on wet pavement due to less friction.
Combining these distances gives the total stopping distance required after the driver perceives a need to stop. In the scenario where debris falls in front of the car, resulting in a 30.5 m (100-feet) skid mark, it indicates that the car was likely traveling over the 30 mph speed limit, assuming the coefficient of friction between the tires and the road was 0.55.