1. Seismic Waves Lab

2. Question/Purpose:
To determine which type of earthquake wave: P (pull-and-push) or S (side-to-side) travels at a faster speed.

3. the speeds of S-waves and P-waves are measured
Hypothesis/Prediction:
IF…
the speeds of S-waves and P-waves are measured
THEN…
the P-wave (pull-and-push) will travel at a faster speed. OR
the S-wave (side-to-side) will travel at a faster speed.
BECAUSE…

4. Identification of Variables:
Manipulated:
type of wave
Responding:
speed of the wave
Controlled:
distance the wave travels
Force used to create the wave

5. Materials:
1 slinky
1 stopwatch
1 slip of paper
Meter stick
Masking tape
Calculator

6. Procedure: Collect lab materials.
Using the meter stick, measure out a distance of 3 meters on the floor and mark it using masking tape.
Lay the slip of paper on the floor perpendicular to 1 piece of tape.

7. Procedure:
Stretch out the slinky 3 meters by having 2 people hold the ends of it.
Have one person pull-and-push one end of the spring so it sends a wave back and forth through the spring.
Using the timer, the 3rd person should time how long it takes for the wave to travel back and forth in seconds.

8. Procedure: Record the time in the data table.
Repeat steps 5-7 for two additional trials.
Average the times and calculate the speed of the P-wave (speed = distance/ average time) and record.
Lay the slip of paper on the floor parallel to the tape.

9. Procedure: Repeat step 4.
Have one person move one end of the spring side-to-side so it sends a wave back and forth through the spring.
Repeat steps 6 and 7.
Repeat steps 12 and 13 for two additional trials, calculate the speed of the S-wave, and record.
Clean up!

10. Data Table: Wave Speed Speed = Distance (6 meters) Time (seconds)
Type of EQ Wave
Time Trials
Distance
(m)
Speed
(m/s)
Pull and Push
(P-wave)
Trial 1
(S)
Trial 2
Trial 3
Average
Time (S)
Side to Side
(S-wave)

11. Analysis:
1. Analyzing Data: According to your data, which wave traveled the fastest and which one traveled the slowest? 2. Drawing Conclusions: What is the relationship between wave speed and the amount of time it took for the wave to travel 6 meters? 3. Formulating Hypotheses: Based on your observations, form a hypothesis about the relationship between wave type and speed. 4. Predicting: What would your results have been if the distance the wave traveled increased to 12 meters? Would your conclusion be the same or different? Explain. 5. Inferring: When an earthquake occurs and energy is released in the form of waves, which type of seismic wave would be first detected by a seismograph station? Explain your reasoning.

12. Bar Graph:
Construct a bar graph of the average speeds for the 2 types of waves.
Remember: title, label both axes, and include units!

13. Conclusion:
Write a conclusion following the guidelines outlined on your “How to Write an 8th Grade Lab Report” sheet.

14. Lab report due Friday @ the start of class!
Today's Checklist
Complete the lab and fill out data table.
Construct a bar graph of the average speeds for the 2 types of waves. (Remember: title, label both axes, and include units)
Answer the analysis questions [IQIA]
Write a conclusion following the guidelines outlined on your “How to Write an 8th Grade Lab Report” sheet.
Lab report due the start of class!