Seismic Waves Lab

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

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…

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

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

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.

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.

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.

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!

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)

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.

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

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

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 Friday @ the start of class!