Geology module 1

Background Information: After you read the book chapters, reviewed the slides, and watched the videos, I hope you are able to explain why earth has layers: earth is made of different elements that have different densities. During the early formation of the earth, less dense elements rose toward the surface and denser elements sank toward the center of the earth which led to the formation of layers. In this activity, it provides you further evidence why the core has a small volume percentage relative to the whole earth volume, but it accounts for a much bigger weight percentage of the earth. Ultimately, I am hoping you reach the conclusion that the earth core is made of denser elements (such as iron and nickel) compared to the mantle and crust. Complete the questions below and see it yourself. Earth’s Layering 1. Calculate the % of the whole volume of the Earth that is occupied by the core and mantle, respectively. The formula of the volume of a sphere is 4 3 πr 3 where r is the radius of the sphere and π=3.14. The radius of the Earth is 6371 km, the radius of the core is 3471 km. The crust is so thin relative to the mantle and the core that you can ignore it in your calculations. PLEASE SHOW EACH STEP THAT LEADS TO YOUR FINAL ANSWER. Tips for this question: 1) don’t be scared of numbers, you’ll have fun with them once you like them; 2) calculate the volume of the whole earth first using the given equation 4 3 πr 3 ; 3) then calculate the volume of the core using the given equation 4 3 πr 3 ; 3) now you can use the volume of the core divided by the volume of the whole earth to get the percentage of the core; 4) use 100% minus the percentage of the core you get in the previous step to get the percentage of the mantle since we are ignoring the volume of the crust. Here is my example on how to calculate the earth’s volume using the given equation: V= 4 3 πr 3 = 4 3 *3.14 * (6371 km) 3 = 1.08 x 10 12 km 3 4 3 πr 3 = V πr= 3.14 4 3 *3.14 * (3471 km) 3 / = 4 3 *3.14 * (6371 km) 3 = 25.82% r=3471 km 2. Now you have calculated the % of the mantle and core relative to earth by volume , respectively. Scientists have also calculated the % of the mantle and core relative to the earth by weight , which are 68% and 31%, respectively. Explain why the percentages are very different in terms of volume vs. weight. (Hint: think about which layer is composed of the densest elements…)