PHY 102: Exam and Homework Q's and Answers

Which of the following are parts of the scientific process, as described in class? (Check all that apply). Answer- A. building a theory or hypothesis E. careful observation or measurement F. experimental tests of a hypothesis H. modification of the model or theory (if needed) The speed of light, c, (measured in meters/second) is...? Answer- E. 300,000,000 A light year is... Answer- C. a unit of distance Color, Wavelength, Frequency, and Energy are all equivalent descriptions for a particular type of light wave. Answer- A. True The energy of light is directly proportional to its... Answer- frequency Which of the following definitions correctly describe the ecliptic? (Check all that apply) Answer- B. the plane in which the Earth orbits the Sun D. the apparent path of the Sun relative to the background stars E. the apparent path of the Sun on the celestial sphere Which of the following explanations correctly describes the reason we see the Sun rise and set each day? Answer- D. The Earth rotates on its axis Which of the following explanations correctly describes the reason Earth's Moon shows phases? Answer- B. The changing angle between the Sun, Moon, and Earth causes a variable fraction of the Moon's surface to reflect sunlight Which of the following are a consequence of the Earth's yearly motion around the Sun? (Check all that apply) Answer- C. different stars are seen at night at different times of the year D. the Sun appears in different constellations in different months E. the Sun changes its height in the sky in different seasons Which of the following explanations correctly describes the reason Earth experiences seasons? Answer- A. The Earth's Northern hemisphere is tilted 23.5 degrees toward the Sun in Summer and away from the Sun in Winter During a partial lunar eclipse... Answer- F. The Moon is partially within the Earth's umbra During an annular solar eclipse... Answer- F. The Moon covers all but the outer ring of the Sun The Ptolemaic cosmology (Claudius Ptolomy's model of the solar system) was predominantly believed for many centuries in Europe. Which statement below is FALSE about the Ptolemaic system? Answer- C. It was much simpler than the earlier models and therefore not as accurate. Of the cosmological models listed below, which placed the Earth at the center of the model? (Check all that apply) Answer- A. Ptolemaic (Claudius Ptolomy) B. Aristotelian (Aristotle) D. Tychonic (Tycho Brahe) Two ingerdients in the scientific method are careful observations, and the formulation of a model (or theory) which adequately explains the observations. The history of astronomy in the post-renaissance period provides a beautiful example of this in the cooperation between... Answer- A. Tycho Brahe's observations, and Johannes Kepler's model The fastest moving planet in our Solar system is... Answer- C. the planet nearest the Sun An engineer who designs "static" structures knows that a particular design is a failure if... Answer- E. the structure becomes too dynamic. A car is parked on a hill. Besides its weight and a frictional force on the tires and brakes, what other force must act in order to keep the car "static"? Answer- D. The normal force: the ground pushing on the car. You're driving down the highway and a bug hits your windshield and sticks there. Which undergoes the greater change in momentum? Answer- B. both undergo the same sized change in momentum In a roller coaster you are taken to the top of the tallest hill, then allowed to coast over the rest of the track. At the lowest point on the track... Answer- C. your kinetic energy is a maximum. A human "cannonball" is shot from a cannon and follows a parabolic path into a net. At the top of her trajectory... Answer- A. None of the other answers are correct (all different types of energy) What happens to the kinetic energy in a TOTALLY elastic collision? Answer- A. Kinetic energy is conserved (it is all recovered and measured as kinetic energy of the objects after the collision). What happens to the kinetic energy in a totally IN-elastic collision? Answer- C. Kinetic energy is completely converted into other forms of energy and none remains after the collision (there is no motion of any of the objects after the collision). Which of the following are true comparisons between the electric force (described by Coulomb's Law) and the gravitational force (described by Newton's Universal Law of Gravitation)? Check all that apply. Answer- A. There are two kinds of charge that are subject to the electric force, but only one kind of mass subject to the gravitational force. C. Gravity only attracts, while the electric force either attracts or repels. E. Gravity depends on the amount of mass involved, while the electric force depends on the amount of charge. F. Gravity is much weaker than the electric force. The flow rate of electric charge is measured in units called Amperes (or amps, for short). What is the equivalent metric measure of one ampere of electric current? Answer- B. one Coulomb/second In the analogy where an electric circuit is like water flowing through a system of pipes, which circuit component would represent the "storage tank"? Answer- D. the capacitor One way to produce a magnetic field, is with... Answer- B. ...an electric current. The magnetic field lines produced by a bar magnet... (Check all that apply) Answer- E. ...always begin on the north pole and end on the south pole. F. ...always form closed loops. The magnetic force on a charged particle... (Check all that apply) Answer- A. ...can cause the charged particle to change its direction of motion. F. ...is zero unless the charged particle is in motion. From the H-R diagram, a star about the same temperature as the Sun, but with much higher luminosity would most likely be... Answer- D. ...a supergiant star. Based on its position on an H-R diagram, our Sun is... Answer- D. ...a pretty average, typical main sequence star. Based upon the information in an H-R diagram... Answer- B. ...the cooler main sequence stars would have a lower luminosity. The main nuclear reaction which powers the Sun is... Answer- C. ...fusion of hydrogen into helium. Nuclear fusion uses up the hydrogen (chemical symbol H) in a main sequence star's core by... Answer- A. ...combining 4 H nuclei to form 1 helium, and in the process, converting some of the mass into a large amount of energy. Which type of star is most likely to explode as a supernova at some point in the future? Answer- E. A supergiant star Compared to the Sun, main sequence stars with much larger mass... Answer- E. ..."burn" their hydrogen fuel more rapidly than the Sun. The color which a star appears is most directly related to... Answer- A. ...its surface temperature. Sending an electric current through a gas sealed in a transparent glass tube will result in... Answer- B. ...spectral lines at wavelengths characteristic of the gas (an emission spectrum). Which of the following would be a source of discrete spectral lines (an emission line spectrum)? (Check all that apply). Answer- A. A sodium vapor lamp (like those yellowish street lights). D. A hydrogen gas tube carrying an electric current. What is one reason the Moon's surface is almost entirely covered with craters, while the Earth's surface is not? Answer- B. The Earth's atmosphere protects the surface from meteors. They burn up before they reach the ground. What are some of the major differences between the terrestrial (inner) planets and the Jovian (outer) planets in our Solar System? (Check all that apply). Answer- A. Terrestrial planets have higher densities than the Jovian planets. B. Terrestrial planets have weaker magnetic fields than the Jovian planets. C. Terrestrial planets have much less complicated satellite and ring systems than the Jovian planets. D. Terrestrial planets have less substantial atmospheres than the Jovian planets. E. Terrestrial planets are closer to the Sun and therefore warmer than the Jovian planets. F. Terrestrial planets have slower rotation rates than the Jovian planets. G. Terrestrial planets are less massive and smaller than the Jovian planets. H. Terrestrial planets have rocky surfaces while the Jovian planets have gaseous surfaces. A characteristic of a good scientific theory is that... Answer- E. it is built upon existing knowledge, and testable by experiment A Moon phase that is "gibbous" means that... Answer- B. more than half the Moon is lit up by sunlight The speed of light is measured to be 3.0 x 108 meters/second, which is... Answer- E. faster than any other known phenomenon How do electrons in the Bohr model of an atom move between energy levels? Answer- E. by absorbing or emitting only specific sizes (energies) of photons of light The spiral arms in a galaxy typically contain... Answer- E. all of the above (stars, dust, helium gas, hydrogen gas) The revolution (orbit) of the Earth about the Sun results in... Answer- C. the yearly cycles of changing hours of daylight and Sun's height in the sky In a solar eclipse, the dark, inner portion of the Moon's shadow (which may permit someone to view a total solar eclipse), is known as the... Answer- umbra Which of the following statements is correct for eclipses in the Sun-Earth-Moon system? Answer- C. A total lunar eclipse occurs only at full Moon The collision and interaction of galaxies can occur if they get close enough together. What is responsible for this kind of interaction? Answer- C. gravitational forces The most convenient units to use in measuring the distances to stars is... Answer- D. light-years Velocity is described as a change in position. In a similar way, acceleration can best be described as... Answer- B. a change in velocity When galaxies interact with one another, which of the following observations is NOT something we might see happening? Answer- C. all the stars in the galaxies may die out simultaneously If the Earth's spin axis were perpendicular to the ecliptic plane (point straight up out of the ecliptic plane, rather than tilted), the seasons on the Earth would... Answer- D. occur mostly at the equator instead of at the poles Which of the following statements is true about the energy levels of atoms? Answer- D. Energy levels are "quantized", meaning they are discrete and well-defined The two most important components (steps) of the scientific method are... Answer- C. theory and experiment The Sun (and our solar system) is located where in our galaxy? Answer- B. in the disk, about 28,000 light years (2/3 of the way out) from the center Which of the following is NOT a type of galaxy, in the Hubble "tuning fork" classification scheme? Answer- D. starburst The constellations of the zodiac are more well-known than other star patterns on the celestial sphere, because all 13 constellations lie close to the... Answer- ecliptic If a star in space is observed in both visible light, and microwaves, and found to be much dimmer in visible light, the most likely explanation for this is... Answer- D. the processes going on in the star produce more microwaves than visible light When measuring velocity from a graph (like in the first lab, Graphical Analysis), to find the slope of the graph, it is necessary to measure the difference between... Answer- E. two positions at two separate times While driving from Bloomington/Normal to Chicago, A person drives the first 50 km at a velocity of 100 km/hr, then stops for half an hour, then drives the remaining 150 km at a velocity of 90 km/hr. What is the average velocity for the total trip? Answer- B. 75 km/hr Isaac Newton discovered that white light, when passed through a prism, would spread out into a spectrum of all the visible colors of the rainbow. When those colors were passed through a second prism, Newton found that they... Answer- C. recombined to form white light again The monthly cycle of Moon phases can best be explained by... Answer- D. the revolution of the Moon around the Earth, and the angle of sunlight Suppose you look up in the sky one evening at about 6 PM, and directly overhead you see the Moon, half visible, with the left half dark, and the right half illuminated. In about 7 or 8 nights, if you look for the Moon again, you are likely to find that its phase will be... Answer- C. full moon The seasons on Earth result because... Answer- D. Earth's spin axis is tilted 23.5 degrees relative to the ecliptic, causing alternately uneven heating of Earth's northern and southern hemispheres The celestial sphere... Answer- B. is an imaginary sphere around the Earth with the stars all fixed upon it D. is a coordinate system for the sky, similar to latitude and longitude The lowest frequency ranges of light waves (radio waves and microwaves)... Answer- A. are low energy, and therefore relatively safe for human exposure Once a scientific theory has been established, what would need to happen in order to consider changing, abandoning, or replacing it? Answer- C. multiple new observations made by independent scientists would need to contradict the predictions of the theory All Helium atoms contain the same number of protons in their nucleus. Answer- True Frequency and color are two equivalent ways of specifying a type of light wave. Answer-