Final answer:
The average speed of a train is the total distance traveled divided by total travel time, and the average velocity is displacement divided by time. With a round trip and return to the point of origin, average velocity is zero.
Step-by-step explanation:
The question relates to understanding the average speed and average velocity of a train on a journey. When a train travels a certain distance and returns back to the starting point, as in the example from Baltimore to Washington, DC, and back in 1 hour and 45 minutes over 40 miles, we can calculate these two quantities.
The average speed is the total distance traveled divided by the total time of the journey, whereas the average velocity is the displacement divided by time. Since the train returns to its starting point, the total displacement is zero, resulting in an average velocity of zero.
To calculate average speed in meters per second (m/s), we follow these steps:
- Convert the total distance traveled into meters (which is 80 miles for the round trip; 40 miles each way).
- Convert the total journey time into seconds.
- Divide the total distance in meters by the total journey time in seconds.
An essential point to note is that if a train spends 10 minutes at a checkpoint, this time contributes to the total duration of the journey but does not affect the total distance traveled. Thus, the duration of the journey includes all stops, such as the 10 minutes at the checkpoint in question.