Final answer:
The smallest number on an odometer indicates the total distance a vehicle has traveled. To calculate the average speed, divide the total distance traveled by the time of the trip, whereas the magnitude of the average velocity requires considering direction, and they're identical only when displacement is zero.
Step-by-step explanation:
The smallest number on a car's odometer indicates the total distance covered by the vehicle. An odometer is an instrument used to measure the distance traveled by a vehicle, and it does not provide information on fuel consumption, engine temperature, or speed. When you calculate the average speed of a car by dividing the total distance traveled (as determined by the odometer) by the total time for the trip, you are not calculating the magnitude of the average velocity unless the start and end points are the same, which would make displacement zero. Instantaneous speed, which a speedometer measures, is the speed of a vehicle at a specific moment in time and differs from velocity because it does not account for the direction of the movement.