some questions 5

1. The Earth’s interior currently holds approximately 1017 kg of Uranium-238, which has a half-life of 4.5 billion years. How much was present when the Earth first formed? If the Sun expands and consumes the Earth 9 billion years from now, how much U-238 will be left just before we are engulfed?

(You may write your answer using Canvas’ equation editor to express scientific notation, or use the shorthand from Homework 1, where 1017 is expressed as 1E17.)

2.What is Pluto’s escape velocity, in kilometers per second?

3.If Pluto’s surface temperature is 50 K, what is the thermal velocity of a nitrogen molecule in meters per second?

4.Based on your answers to problems 2 and 3, do you think it is likely Pluto has a nitrogen-rich atmosphere like Earth’s?

5. Explain the difference between an S-wave and a P-wave. How do the two give insight into the Earth’s interior?

6.Why do we call CO2 a “greenhouse gas”?

7.Why is the Earth’s magnetic field important for life? How is it generated?

8.What is subduction? How does it help regulate Earth’s climate?

9.In what two ways is a planet’s atmosphere responsible for allowing liquid water on its surface?

10. What is the primary source of the recent massive increase in carbon dioxide in the Earth’s atmosphere? How do we know?

11.In what two forms is oxygen found in Earth’s atmosphere? How is each important for life?