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Geosciences LibreTexts

2.8: Student Responses

  • Page ID
    5466
  • 1. Observe the velocities of the waves on the graph. Which one travels faster?

    a. P waves                         b. S waves

     

    2. Inspect the P wave velocities. Where do the P wave velocities abruptly change?

    a. ~20 km                         b. ~2,900 km                         c. ~5,100 km                         d. All of the above

     

    3. In which zones do the P wave velocities appear to be steadily increasing?

    a. ~20–2,900 km               b. ~2,900-5,100 km                c. ~5,100-6,400 km                d. Both a & b

     

    4. Observe the S wave velocities. Where do the S wave velocities abruptly change?

    a. ~20 km                        b. ~2,900 km                          c. ~5,100 km                         d. All of the above

     

    5. At ~2,900 km, the S wave velocity falls to 0. Why?

    a. S waves can’t travel through solids, and this depth is where the solid inner core exists.

    b. S waves can’t travel through liquids, and this depth is where the liquid outer core exists.

    c. S waves can’t travel through solids, and this depth is where the solid mantle exists.

    d. S waves entered the shadow zone.

     

    6. The zone from ~0-20 km represents the Earth’s:

    a. crust                          b. mantle                          c. inner core                          d. outer core

     

    7. The zone from ~20-2,900 km represents the Earth’s: 

    a. crust                          b. mantle                          c. inner core                          d. outer core

     

    8. The zone from ~2,900-5,100 km represents the Earth’s: 

    a. crust                          b. mantle                          c. inner core                          d. outer core

     

    9. The zone from ~5,100-6,400 km represents the Earth’s:

    a. crust                          b. mantle                          c. inner core                          d. outer core

     

    10. Measure the distance, using the bar scale, between the pole in 1400 and 1500 (locations C and D). How far did the pole move?

    a. ~50 km                             b. ~150 km                             c. ~600 km                             d. ~1,000 km

     

    11. How far (in km) did the pole move in one year during this time period?

    a. 0.5 km                              b. 1.5 km                                c. 6 km                                   d. 10 km

     

    12. How far did the pole move in meters in one year during this time period?

    a. 1,500 m                            b. 500 m                                 c. 10,000 m                             d. 6,000 m

     

    13. Approximately how far did the pole move per day?

    a. <1 m                               b. ~16 m                                 c. ~20 m                                 d. ~12 m

     

    14. Measure the distance, using the bar scale, between the pole in 1400 and 1700 (locations C and F). How far did the pole move?

    a. ~50 km                            b. ~150 km                             c. ~600 km                              d. ~1,000 km

     

    15. Do pole movements tend to be steady every 100 years or variable?

    a. movements are steady                                                    b. movements are variable

     

    16. Search for the “Washington Monument” and zoom into ~3,000 feet eye altitude. What is the latitude of the monument?

    a. 38º 53’N                         b. 38º 53’S                         c. 77º 02’E                         d. 77º 02’W

     

    17. What is the longitude of the monument?

    a. 38º 53’N                         b. 38º 53’S                         c. 77º 02’E                         d. 77º 02’W

     

    18. Zoom into an eye altitude of ~500 feet. Locate the base of the monument (the base is square and is located in the center of the circle). What is the elevation of the base of the monument in feet?

    a. 15 feet                           b. 40 feet                           c. 65 feet                           d. 80 feet

     

    19. What is the elevation of the base of the monument in meters?

    a. 40 meters                      b. 25 meters                       c. 12 meters                       d. 7 meters

     

    20. How big is the base (area) of the Washington Monument in square feet? (Hint – make sure the 3D Buildings is selected in the Layers box, located in the lower left of the screen. Also, area is measured in square feet. So, make sure you are multiplying two measurements.)

    a. ~1040 ft2ft2                   b. ~3100 ft2ft2                   c. ~4700 ft2ft2                   d. ~6030 ft2ft2

     

    21. If you were standing at the Washington Monument, what direction would you need to walk to go to the United States Capitol Building?

    a. North                            b. East                               c. South                             d. West

     

    22. The direction system is useful, but imprecise. It is better to use a bearing. If you were standing at the Washington Monument, what bearing would you need to walk to go to the Smithsonian National Museum of Natural History, which houses many important geological specimens (Hint: Many of the buildings on the National Mall are part of the Smithsonian – make sure you get the correct building!)?

    a. 30º                               b. 75º                                c. 90º                                d. 260º

     

    23. If you decided instead to walk from the Washington Monument to the White House, how far would you have to walk, in miles (assume you could walk right to the entrance of the building)?

    a. 0.56 miles                     b. 0.78 miles                       c. 1.20 miles                       d. 1.87 miles

     

    24. How far is this distance in kilometers?

    a. 0.5 kilometers               b. 0.9 kilometers                  c. 1.4 kilometers                 d. 1.9 kilometers 

     

    25. Overall, would you be walking uphill or downhill?

    a. No change in elevation                             b. Slightly uphill                             c. Slightly downhill

     

    26. How much does the elevation change in feet?

    a. 0 feet                          b. 10 feet                            c. 20 feet                           d. 30 feet

     

    27. What is the gradient of your walk?

    a. ~0.003                        b. ~0.05                             c. ~0.5                               d. ~1

     

    28. You decide to start walking from the Washington Monument to the White House, but as soon as you start a Park Ranger yells at you for walking on the grass. How far would the walk be (in miles) if you stayed on the sidewalks? There are many possible routes – try to take one of the shortest routes possible.

    a. 0.5 miles                     b. 0.8 miles                         c. 2 miles                            d. 5 miles

     

    29. Now, let’s look at a geologic feature. Put 36 05 35.38 N 113 14 43.70 W into the search bar and zoom out to an eye altitude of ~25,000 feet. This is the Grand Canyon. If you started out in Washington, D.C., what bearing would you need to travel in to go to the Grand Canyon?

    a. 210º                           b. 245º                               c. 275º                               d. 315º

     

    30. The Grand Canyon is an extraordinarily steep area. If you go from the river at the bottom of the Canyon (36 05 35.38 N 113 14 43.70 W) straight north up the canyon rim (the area that flattens out above the red layers of rock – 36 06 10.12 N 113 14 48.88 W), what is the gradient of the Grand Canyon? (Hint: You can tilt the image, which will make the flat rim easier to see, by either pressing down on the middle mouse wheel and moving the mouse forward and backward or by clicking on the arrows above and below the eye in the upper right-hand portion of the window.)

    a. 0.214                         b. 0.673                               c. 0.976                             d. 1.245