Physics

Study Questions for Geophysics

http://www.csus.edu/indiv/s/slaymaker/archives/sqgeophysics.htm

STUDY QUESTIONS FOR GEOPHYSICS
State the Law of Universal Gravitation State Newton's Second Law. Using the Law of Universal Gravitation and Newton's Second Law, derive an expression for the acceleration of gravity. What is the approximate value for the acceleration of gravity? What is the unitused for the acceleration of gravity? How many cm/sec2 is it equal to? How do we know that the interior of the Earth must be composed of rocks denser than those on the Earth's surface? Define and give formulas for angular momentum, moment of inertia? What causes the Earth's oblateness? Define: spheroid geoid What is the name of the formula used to calculate the theoretical value of "g" at anylatitude? In what two ways may one measure the actual value of g at a particular location? What are the disadvantages to using a pendulum to measure g? How high are "solid Earth" tides? What is a gravity anomaly? a positive gravity anomaly? a negative gravity anomaly? Name the reasons why the actual value of g measured at a particular place is not the same as the theoretical value. What correctionsare applied to: a. "correct" actual values of g to remove that portion due to the mass between sea level and the elevation at which g was measured, 2. correct actual values of g to remove the effects of nearby mountains and valleys, 3. correct actual values of g to sea level? Define: Free Air anomaly Bouguer anomaly Which of the three most commonly applied corrections is the least important and isoften ignored? If not ignored, how is the corrections usually made? Why is the topographic correction always added to the measured value? What are the characteristic values for Bouguer Anomalies in the following places? mountain regions continental shields

1 of 8

3.11.2012 15:04

Study Questions for Geophysics

http://www.csus.edu/indiv/s/slaymaker/archives/sqgeophysics.htm

oceansHow are positive anomalies produced? negative anomalies? Describe Pratt's and Airy's concepts of isostasy. Which is probably correct? How can the viscosity of the mantle be determined? Where are regional anomalies produced (how far down?) What is another name for small scale anomalies which remain after regional anomalies are removed? Outline the procedure for interpreting gravity anomalies. Whatkinds of anomalies (sign and shape) would be produced by the following geologic features? salt domes sedimentary basin mass of granite ultramafic mass buried ridges and valleys anticlines synclines oceanic trenches oceanic ridges fault buried stream channel continental crust/oceanic crust boundary What evidence is there from gravity studies that all granite cannot have been produced bydifferentiation? What is a gravity gradient? How can gravity gradients be useful in locating anomalous bodies? What is geochronology? What is radioactivity? What changes take place during radioactive decay? Define half life, parent element, daughter element. What assumptions are routinely made in radiometric dating procedures? What are isochrons? How are they obtained? How can Rb, Sr dating and K, Ardating be used to determine age of metamorphism? How can Rb, Sr be used to determine crustal vs. mantle origin of rocks? How can the 87Sr/86Sr ratio be determined for current mantle rock? for older mantle rock? In a 238U -> 206Pb study, the original ratio of 206Pb/204Pb must be known. How can this be determined? What are concordant ages? discordant ages? What is a concordia curve? How can one be usedin radiometric dating? What is the lead-lead method? Why is it particularly useful?

2 of 8

3.11.2012 15:04

Study Questions for Geophysics

http://www.csus.edu/indiv/s/slaymaker/archives/sqgeophysics.htm

How can 238U -> 4He be used to determine solidification ages? Where has this method been used? What problems are there with this method? How are U and/or Pb used to determine the...