Establish a known distance: The officer chooses a straight section of road with a known distance marked by landmarks, such as mile markers or road signs. This distance serves as the reference for measuring the vehicle's speed.
Start the stopwatch: As soon as the officer observes the vehicle passing the starting point of the known distance, they start the stopwatch.
Observe the vehicle: The officer keeps the vehicle in sight while it travels along the known distance.
Stop the stopwatch: When the vehicle passes the ending point of the measured distance, the officer stops the stopwatch.
Calculate the average speed:
1. The officer records the elapsed time displayed on the stopwatch.
2. They then divide the known distance by the elapsed time to determine the average speed in units such as miles per hour or kilometers per hour.
For instance, if the known distance is 0.25 miles and the stopwatch shows an elapsed time of 10 seconds, the average speed would be:
Speed = (0.25 miles / 10 seconds) * (60 seconds / 1 minute) * (60 minutes / 1 hour)
= 0.025 miles / second * (60 * 60)
= 9 miles per hour
It's important to note that this method assumes the vehicle maintained a constant speed throughout the measured distance. If the vehicle accelerated or decelerated, the calculated average speed may not accurately represent its actual speed at any specific moment.
