Science Buddies: "Ask an Expert"

From a parent/student working on the following project: https://www.sciencebuddies.org/science- ... ml#summary

I have the Trigonometry formula to solve for the diameter. My main problem is how to plot the data based on the information in the graphs. I do see the distances but how do we take the data and place in a graph to determine the diameter? The GEE program does have a time travel calculator I wonder if this calculator can also determine the diameter? It provides data on the S waves and the P waves. The project is very detailed on how to create the data however it does not explain well on how to calculate or interpret the data.

Hi:

I hope this can help a little with your problem.

My main problem is how to plot the data based on the information in the graphs. I do see the distances but how do we take the data and place in a graph to determine the diameter?

First, doesn't the GEE plot the data for you? In the procedure, steps 6 c-e, there is a description of how to get the graph you need from the GEE. Did you get this graph? If so, can you find the angle where the S wave disappears? If you can, then you can use that angle to find the radius of the core. If I look at figure 4 in the Background section, the line marked "?" is the radius of the core. It bisects the angle marked "105 degrees". To find this distance, you will use half of the angle measured (that's what bisects means, it cuts the angle in half.) From the half triangle, the cosine of the 1/2 angle is the core radius divided by the radius of the earth. The formula is (radius of core) = (radius of earth) times cosine ( GEE angle divided by 2 ). Please let us know if you still have more questions.

Keith