Plate Tectonic - Earthquakes (6)
Lab 


PROBLEM:
Do waves pass through different substances differently?

PREDICTION:

PROCEDURE: Earthquakes produce seismic waves. This lab will explore how waves behave as they travel through different substances.

EXERCISE I. 
MATERIALS:
4 pennies, 4 nickels, graph paper

  1. Place 1 penny about 8 inches away from another penny on top of the graph paper. Snap one penny into the other. Record the motion of the penny and how far the penny moved. (Click here for example.)
  1. Repeat the exercise, replacing one penny with a nickel. Use the same amount of "snap" as in the picture below. Record what happens.
                        

                                                           

  1. Place the pennies as in the picture below.
    Snap one penny. Record what happens
                                  .
      

  2. Repeat the exercise using nickels. Record what happens.
      

  3. Repeat #4, except use one penny behind the shooting line. Is there a difference?
    If so, why?

EXERCISE II.
MATERIALS:
density timer
Tap one side of the density timer. Do the waves travel differently through the oil and water? Record what happens.
  
EXERCISE III.
MATERIALS: 1 balloon filled with water, one balloon filled with air.
Tap the side of each balloon. Is there a difference between the two? Why?

CONCLUSION: If waves go through different substances at different speeds, how can we use this information to determine what is inside the earth?

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