1. Part B: Kinds of Seismic Waves

2. Pre-Lab Questions What is a seismic wave?
How do earthquakes travel through the Earth?
Do you think there are more than one type of waves that travel through the Earth?
What is the device that scientist use to detect earthquakes?

3. What do Know/Complete the Following

4. Materials Needed Meter stick
Part B: Kinds of Seismic Waves data sheet.
Slinky
Stopwatch
Calculator
Speed formula

5. Goal
To observe two kinds of seismic waves: compressional and shear waves. Learn how scientists study the arrival times and amplitude of seismic waves. How seismic waves are used to study the interior of the Earth.

6. Compressional and Shear Wave DEMO

7. Compressional Wave
Holding the end of the slinky I will make a quick up and down motion. Then I will make a slow up and down motion.
Answer the following:
What happened when the slinky made the fast up and down motion?
What happened when the slinky made the slow up and down motion?
Does the wave move in the same direction as the slinky or in the opposite direction.

8. Shear Waves
Holding the end of the slinky I will make a quick side to side motion. Then I will make a slow side to side motion.
Answer the following questions.
a. What happens when the slinky made the fast side to side motion?
b. What happened when the slinky made the slow side to side motion?
c. Does the wave move in the same direction as the slinky or in the opposite direction.

9. Inquiry
Based on the demonstration… Which wave do you think travels the fastest and why?

10. Notes Compressional waves: - push and pull motion
- have the same direction of vibration as their direction of travel (parallel)
- waves act like an accordion.
2. Shear waves:
- side to side motion.
- have 90 degree motion of vibration as their direction of travel (perpendicular)
- waves act like a snake.

11. Activity Obtain a slinky and data sheet.
Conduct 2 different experiments: Part 1 and Part 2.
a. Part 1. using a distance of 4 meters
b. Part 2 using a distance of 2 meters
Part 1.
Stretch the slinky out to a distance of 4meters.
Start with the up and down movement.
Procedure
a. Flick your wrist to create this movement.
b. Start the stopwatch at the wrist flick.
Stop the stopwatch when the first wave hits your partners hand.
Complete 15 trials.

12. 4. Part 1. Continued
a. Stretch the slinky out to a distance of meters.
b. Use the side to side movement.
c. Procedure
a. Flick your wrist to the side to create this movement.
b. Start the stopwatch at the wrist flick.
Stop the stopwatch when the first wave hits your partners hand.
Complete 15 trials.

13. Part 2. Stretch the slinky out 2 meter.
Use the same steps from part 1…

14. Side by Side Comparison
Stretch out 2 slinkys side by side to a distance of 4 meters.
Starting at the same end one student will do the side to side motion while the other will do the up and down motion.
Try it several time
Which wave arrived first.

15. Data
Find the Average time, in seconds, for all parts of the experiment.
Find the average speed, (m/s), for all parts of the experiment.
Work should be completed in your notebook and data placed in the data sheet.

16. Part B: Post Questions
What determined whether the wave travels the length of the slinky?
How do the coils change as the wave passes? In a p-wave. In a s-wave.
What happens when the wave reaches the other end?

17. Post Questions Continued
4. How does the wave travel compared to the orientation of the slinky? In a p-wave. In a s-wave.
5. Do you think waves travel through rock?
6. In a side by side comparison, which wave type would arrive at the other end first? Explain why you think this happens.