NSc 105 (Fall 1996) Second Exam: Oct 1996 Page 1 Second Exam (100 points) Name ______________________ This exam is closed book, closed notes. Please note that for some sections you will have a choice of which questions to answer. Read all instructions. The questions are not meant to be tricky. If you have a question about what is being asked, please raise your hand. Good luck! True/False. Answer all questions by circling the best choice. There are ten 'real' questions and one bogus question. The bogus question is not to be taken internally, and will not be graded. (1 point each; 10 points total). T F 1. Materials in which few electrons are free to move make good electrical insulators. T F 2. Protons and electrons have just about the same mass. T F 3. 'Compressive strength' and 'tensile strength' can differ for a material. T F 4. Somebody, somewhere voted for somebody or something today that will impact my life. T F 5. A flashlight illuminates objects with electromagnetic radiation. T F 6. The density of the Earth as you go deeper tends to decrease. T F 7. The Doppler effect describes how the frequency of a sound wave changes when its source is moving. T F 8. The Earth's magnetic field sometimes spontaneously changes polarity. T F 9. Rocks which are now found at the tops of mountains might once have been sediments on the ocean floor. T F 10. Scientists have found that North America is moving further from Europe at a rate of about two inches per year. T F 11. The Grand Canyon is an example of what happens when two tectonic plates scrape past each other. Mulitple Guess. Answer all questions by circling the best choice. (2 points each; 30 points total). 1. A particular isotope has a half-life of 60 minutes. If we start with a sample of 2000 atoms now, in two hours we will have about how many left? a. 1000 atoms. b. 500 atoms. c. 250 atoms. d. 125 atoms. e. 100 atoms. 2. One characteristic of radioactivity is that it a. occurs in nature. b. is due to a shift in the electrons in the atom. c. can be removed from the environment completely by appropriate action. d. has never been used to generate electricity commercially. e. does not occur spontaneously. Multiple Guess, con't 3. The order, from least energetic (least dangerous) to most energetic (most dangerous) type of radioactive decay is: a. gamma, beta, alpha. b. beta, gamma, alpha. c. alpha, beta, gamma. d. gamma, beta, alpha. e. they are all about the same. 4. In the theory of plate tectonics subduction is the process where a. an oceanic plate dives under another plate and into the mantle. b. a continental plate dives under another plate and into the mantle.. c. new plate is created at mid-ocean ridges. d. two plates slide past one another like the San Andreas fault. e. none of the above. 5. The properties of every material depend on a. the kind of atoms. b. how the atoms are arranged. c. the types of bonds. d. all of the above. e. both b and c. 6. What are some ways the Earth's magnetic field is used for navigation? a. Humans use compasses. b. Some one-celled bacteria use an internal magnet to navigate down to the bottom of a pond. c. Some migratory birds can detect the magnetic field of the Earth. d. All of the above. e. The Earth's magnetic field is not used for navigation. 7. What practical use has been found for gamma rays? a. Detecting the speed of a traveling car. b. Controlling destructive interference. c. Treating cancerous tissues. d. Carrying radio signals. e. Cooking food. 8. Which of the following is the same for all kinds of electromagnetic waves? a. Transmission through the atmosphere. b. Frequency. c. Speed. d. Energy. e. Wavelength. 9. Which geologic era in Earth history spanned the largest amount of time? a. Mesozoic. b. Proterozoic. c. Cenozoic. d. Paleozoic. e. None of the above. Multiple Guess, con't 10. Biblical creationism and Darwinian evolution are different ways of attempting to understand life on Earth because a. you can prove creationism but you can't prove evolution. b. new data will not change the tenets of creationism. c. evolution scientists do not estimate the Earth's age. d. you can prove evolution but you can't prove creationism. e. creationism is guaranteed by the U.S. constitution. 11. By volume, from largest to smallest, what are the main layers of Earth? a. Crust, Mantle, Core b. Mantle, Core, Crust c. Mantle, Crust, Core d. Core, Mantle, Crust e. all the same, within our measurement capabilities 12. The difference between nuclear fission and nuclear fusion is that a. you can get energy from the first, but not from the second. b. you can get energy from the second, but not from the first. c. the former splits apart a nucleus, the latter combines two nuclei into one. d. the former combines two nuclei into one, the latter splits apart a nucleus. e. there is no appreciable difference between fission and fusion. 13. Tectonic plates a. coincide with the boundaries of continents. b. coincide with the boundaries of oceans. c. can contain both continental and oceanic crust. d. are found on every known planet. e. are in the same positions they have been since Earth was formed. 14. The Himalayan Mountains are the result of a. two colliding oceanic plates. b. the creation of new crust. c. two colliding plates with continents. d. an ancient, extinct volcanic belt. e. a subduction zone in mid-ocean. 15.Atoms with one electron or one missing electron in their outer shells a. are inert. b. tend to be particularly reactive. c. are no more or less reactive than other atoms. d. tend to be particularly stable. e. are no more or less stable than other atoms. Short Answer. Answer 4 out of 6 questions. If you answer more than 4 questions, only the first 4 will be graded. There is no minimum length for an answer, and you should not need more than a sentence or two for any question. (5 points each; 20 points total). 1. How do isotopes of an element differ from one another? How are they the same? 2. Give an example of something that might happen if a material in your body exceeds its elastic limit. 3. What is the Doppler Effect? Give one example, either from the class or from your own personal experience. 4. Describe the difference between transverse and longitudinal waves. Are sound waves transverse or longitudinal waves? Short Answer, con't: Remember, answer only 4 out of the 5 questions. 5. Match the geological feature on the left with the type of plate boundary on the right. Mid-Atlantic Ridge a. converging b. diverging Andes Mountains c. hot spot d. transform San Andreas Fault e. chaotic Hawaiian Islands 6. What is the difference between fission and fusion? Interpretation. Answer 1 out of the 2 sets of questions below. (20 points). 1. Figure 6-11, p158 here a. The diagram above refers to the electromagnetic spectrum. There are six types of waves indicated on the spectrum by the letters a-f. Match them with the list of types below. (6 points). a.____________ Radio Waves b. ___________ Gamma Rays c. ___________ Infrared Radiation d. ___________ Ultraviolet Radiation e. ___________ Visible Light f. ___________ X Rays b. What does the wavelength of a wave measure (3 points)? What are the units of wavelength (1 point)? c. What is the name of the electromagentic radiation we feel on our hands when we reach out and get close to a fire? (3 points). d. The relationship between wavelength, frequency, and wave speed is Wavelength x Frequency (Hz, or 1/sec) = Speed (m/sec). From the figure above, estimate the speed of light in m/sec to within a factor of ten. (4 points). e. Is the visible portion of the spectrum large (i.e., cover a large range of wavelength or frequency) or small compared to, for example, the Radio Wave portion of the spectrum? (3 points)? f. Extra Credit: At what Frequency (or Wavelength) is the Sun's peak output of energy located (to within a factor of ten)? (4 points). (If you want to know the answer, see p429 of the text after the exam) 2. Interpretation, con't. Remember ... answer only one of these two questions. Essay. Do 1 out of the 2 questions. You may jot down your ideas and organize your thoughts on the back of the previous page. Please write the essay with complete sentences that make your points. Part of the grading will be on the clarity of your presentation. Make sure that you pick a topic you know enough about to write an essay. If you answer both questions, only the first will be graded. (20 points). 1. Describe one frequency range of the electromagnetic spectrum (i.e., radio waves, or infrared, or .) in terms of its frequency or wavelength, including its impact on people. Include at least one example that exists within 1 km of your seat. Essay, con't: Remember ... choose 1 only! 2. Explain the origin of the magnetic stripes observed on the seafloor on either side of mid-ocean ridges and why the stripes are important evidence in support of plate tectonics.