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Which of the following best describes the most widely accepted theory of the solar system's evolution?
A spinning cloud of interstellar dust and gas shrank under the force of gravity, producing a central star and revolving planetesimals.
Astronomers theorize that the solar system formed from a cloud of gas and dust that contracted under its own gravity and began to spin. Most of the cloud gravitated toward the center of this spinning disk, forming the sun. Smaller amounts of matter spun in the separate eddies, creating nuclei around which evolving planetesimals formed.
The graph shows the relationship between the temperature and luminosity of main-sequence stars as depicted on a Hertzsprung-Russell diagram. Which of the following best describes the change in luminosity that occurs as the temperature increases above 10,000 Kelvin?
The Hertzsprung-Russell diagram plots the luminosity of stars as a function of their surface temperature. The luminosity increases upward on the vertical axis, while the temperature decreases left to right on the horizontal axis. The increased steepness of the graphed line above 10,000 Kelvin indicates that the change in luminosity per unit temperature increases at that point.
3. Regional metamorphism, in which large areas covering hundreds of miles are affected, is believed to be primarily the result of:
- C. Horizontal stresses associated with convergent plate boundaries.
- Regional metamorphism occurs during the mountain building and large-scale deformation associated with plate convergences. Large areas of metamorphic rock are formed during these episodes as compared to more limited zones created during contact metamorphism. When two plates collide, the horizontal force creates the pressures and temperatures needed to fold and melt existing rock into metamorphic rock.
Which of the following best describes the underlying principle that allows radiometric dating to be used as an absolute dating technique?
- The decay rate of naturally occurring radioactive elements into other elements is predictable.
- Decay rates for many radioactive isotopes have been precisely measured and do not change under normal conditions on or near Earth's surface. A radioactive element in organic or inorganic material has decayed at the same rate since the material's formation. The date of the material can thus be calculated from the proportion of the original isotope to its stable end product currently found in the material.
5. Shown above is a cross section of a beach showing typical changes in the
contour and form of beach sand along California's coastline between
April 2000 and March 2001. Which of the following explanations best
describes the likely events responsible for the changes in the contour
and form of the beach?
- The small waves during the summer deposited sand on the beach, while the storm waves of winter cut back the beach.
- In general, the stronger the wave action on a beach, the steeper the beach profile. From April through September 2000, the relatively small waves permitted the deposition of sand, which as the summer went on extended the beach further into the ocean. By March 201, the large waves of winter storms had eroded the sand that had been deposited the previous summer, leaving a steep cross sectional profile.
When groundwater is pumped from an unconfined sand-and-gravel aquifer, sometimes the amount of groundwater withdrawn exceeds the recharge of the aquifer. Which of the following is the most likely consequence of withdrawing more water from this kind of aquifer than is naturally recharged?
- The water table will be lowered, and water from streams, lakes, and wetlands will move downward into the aquifer in response to the decrease in groundwater elevation.
- Unconfined sand-and-gravel aquifers are very permeable, permitting easy movement of water from the surface into the aquifer. When the amount of groundwater drawn from such an aquifer exceeds its recharge rate, the water table surrounding the well will drop to form a conical depression with the lowest point being at the well's uptake. Since streams, lakes, and wetlands overlying an unconfined aquifer are surface expressions of the elevation of the aquifer, the elevation of the water in these water bodies will also drop as they drain downward in response to the drop in elevation of the water table.
Which of the following best describes the process of fossil fuel formation?
- Fossil fuels form over millions of years from the buried remains of organic matter deposited in low-oxygen aqueous environments.
- Fossil fuels take millions of years to form from organic material deposited in low-oxygen aquatic environments, such as swamps and certain marine settings. The lack of oxygen inhibits decomposition by microorganisms, and sediments cover the remains and partially preserve them. As the organic material is buried deeper, the increasing pressure causes chemical reactions to take place, transforming the material into carbon-rich coal, natural gas, and oil.
The international emphasis on the recycling of aluminum has been successful primarily because:
- The extraction of aluminum from ore uses a significantly greater amount of energy than recycling.
- It is extremely energy-intensive to extract and purify raw ore. Although recycling also requires energy and wastes some material, it is nonetheless a more energy, and cost-efficient process. These factors have increased efforts to promote recycling.
In the early 1800s, Thomas Young directed a beam of coherent light at a barrier that had two slits cut into it. He then observed the pattern of light produced on the other side of the barrier. This was one of the most important experiments in research related to:
- Understanding the wave nature of light.
- Thomas Young's experiment provided evidence of the wave-like nature of light. When a beam of light of a single color was directed through two slits, Young observed alternating light and dark bands where the light passing through the two slits recombined. Young interpreted these findings as an interference pattern characteristic of waves, in which two colliding wave crests enhance each other, while a crest and trough cancel each other out.
A converging lens is used to create an image of the arrow labeled X. If the focal length of the lens is 0.1 m, then the image that forms at the point labeled Y will be:
- real and inverted
- Since the arrow is further from the lens that the focal point (0.01 m), the image formed is both inverted and real, i.e., able to be projected onto a surface. As shown in the diagram below, three reference light rays passing through the arrow’s point converge on the opposite side of the
- lens to determine the image’s size and orientation.
- Ray A goes parallel to the axis from the arrow point to the lens and
- then is refracted through focal point F. Ray B passes in a straight line
- directly through the center of the lens. Ray C passes from the arrow
- point through focal point F and then is refracted so it exits the lens
- parallel to the axis. The place where these rays converge indicates
- where the point of the projected arrow image will appear.
The equation v=a�t is sometimes used to find velocity when acceleration and time are known. Another form of this equation is v=v0 + a�t. In this second form of the equation, the function of the term v0 is to:
- Allow the equation to be used even when an object has a nonzero initial velocity.
- In the equation v = a�t, v = velocity, a = acceleration, and �t = the change in time. This equation assumes that the starting velocity equals 0 and can only be used to determine the velocity of an object initially at rest. If the object is already moving, then its velocity can be taken into account by adding v0, where v0 = the starting velocity taken at any point during the motion.
Use the diagram to answer the question that follows:
a cube 10 cm wide, 10 cm high, 5 cm deep
The rectangular solid in the diagram is made of a material that has a
density 25% that of water. If it is placed in a container of water, how
many cubic centimeters of the rectangular solid will be below the
surface of the water?
The depth to which an object will be submerged is based on how much water the object’s weight can displace. If the object’s density is only 25% that of water, then it can only displace 25% of an equal volume of water. When the rectangular solid floats in the water, the upward buoyant force exerted by the water equals the downward force of the solid’s weight. This balancing of forces occurs when 25% of the solid’s volume, or 125 cm3, is submerged.
A force of 100 N is applied to piston X. What is the upward force applied by piston Y?
- 400 N
- Pascal's law states that pressure applied to an enclosed fluid is transmitted equally throughout the liquid and container walls. Therefore when 100 N of force is applied to piston X, the pressure of the enclosed water increases throughout the container and exerts a force on piston Y equal to the ratio of the areas of the two pistons. Since the area of piston Y is four times that of piston X, the upward force of piston Y is four times 100 N, or 400 N.
- 14 In the early twentieth century, Robert Millikan created electrically charged oil droplets and then determined their electrical charge by calculating the magnitude of the electrical charge that would suspend them in midair in opposition to gravity. He found that the electrical charge on each oil droplet was always an integer multiple of what we now know as the basic unit charge. Millikan's experiment is credited with discovering:
- A. The charge on a single electron.
- Each electron carries an electrical charge approximately equal to -1.60 x 10-19. Robert Millikan discovered this experimentally by showing that the oil droplets had an electrical charge equal to some whole-number multiple of this number. After measuring the charge of thousands of oil droplets, he calculated the charge for a single electron by noting the smallest possible difference in charge found between the oil droplets.
In the early twentieth century, Robert Millikan created electrically charged oil droplets and then determined their electrical charge by calculating the magnitude of the electrical charge that would suspend them in midair in opposition to gravity. He found that the electrical charge on each oil droplet was always an integer multiple of what we now know as the basic unit charge. Millikan's experiment is credited with discovering:
- The charge on a single electron.Each electron
- carries an electrical charge approximately equal to -1.60 x 10-19.
- Robert Millikan discovered this experimentally by showing that the oil droplets had an electrical charge equal to some whole-number multiple of
- this number. After measuring the charge of thousands of oil droplets, he calculated the charge for a single electron by noting the smallest possible difference in charge found between the oildroplets.
The device in the diagram consists of two windings of wire wrapped around an iron core. The windings are separate from each other, and neither is in direct contact with the other. There are 200 windings of wire on the input side and 50 windings of wire on the output side. The device most likely performs which of the following functions?
- decreasing voltage
- This device is a step-down transformer used to decrease voltage. Each output-side winding receives the same voltage, induced magnetically from the alternating current in the input windings. The voltages of the output windings simply add together: more windings give a proportionate increase in voltage, fewer windings give a proportionate decrease. Thus, if more input than output windings are present, the voltage will drop.
16. Complete the exercise that follows.
Using your knowledge of the hydrologic cycle:
Draw and label a
diagram of the hydrologic cycle that includes all the pathways of the
cycle and the physical processes involved; and
Describe the transfer of energy between water and the environment as water evaporates and condenses.