Does the speedometer of a car read average speed or instantaneous speed?
How do you know?
The correct answer and explanation is:
The speedometer of a car reads the instantaneous speed. This is because it measures how fast the car is moving at any given moment in time, rather than providing an average speed over a period of time. The speedometer uses sensors that detect the rotational speed of the wheels and translates that into the car’s speed in real-time.
To understand why this is the case, it helps to consider the difference between instantaneous speed and average speed. Instantaneous speed is the rate at which an object moves at a specific point in time. It can vary continuously as the car accelerates, decelerates, or maintains a constant speed. The speedometer provides a reading of this changing speed instantaneously, which is why you see it fluctuate as you drive.
On the other hand, average speed is calculated by dividing the total distance traveled by the total time taken. This measurement includes all fluctuations in speed, including stops, accelerations, and decelerations, and provides a summary of how fast the vehicle has been moving over a period of time. Average speed would require a different kind of measurement, typically done by tracking the car’s position over time and then calculating the total distance covered divided by the total time spent traveling.
In practice, the car’s speedometer is designed to respond quickly enough to show a real-time readout, which makes it an indicator of instantaneous speed. Any delay or smoothing function built into the system doesn’t change the fact that the reading reflects speed at that specific moment, not an average over a longer time span.