Scenario: A snail named Shelly is crawling across a garden. She starts at a point 10 cm to the east of a sunflower and crawls 5 cm east in 10 seconds. She then turns around and crawls 3 cm west in 5 seconds.
Questions:
1. What is Shelly's average speed during the entire journey?
2. What is Shelly's average velocity during the entire journey?
Solution:
1. Average Speed: Speed is the total distance traveled divided by the total time taken.
* Total distance traveled = 5 cm (east) + 3 cm (west) = 8 cm
* Total time taken = 10 seconds + 5 seconds = 15 seconds
* Average Speed = 8 cm / 15 seconds = 0.53 cm/s
2. Average Velocity: Velocity is the displacement (change in position) divided by the total time.
* Displacement is the difference between the final and initial positions. Shelly ends up 2 cm east of the sunflower (10 cm + 5 cm - 3 cm = 12 cm, then 12 cm - 10 cm = 2 cm east).
* Displacement = 2 cm east
* Average Velocity = 2 cm east / 15 seconds = 0.13 cm/s east
Answer:
* Shelly's average speed is 0.53 cm/s.
* Shelly's average velocity is 0.13 cm/s east.
Key Points:
* Speed is a scalar quantity, meaning it only has magnitude (how fast).
* Velocity is a vector quantity, meaning it has both magnitude and direction.
* Even though Shelly traveled a total distance of 8 cm, her final position was only 2 cm east of her starting point, which is her displacement.
