Final
What kind of plate boundary separates the South American Plate from the African Plate?
A divergent boundary. The Mid-Atlantic Ridge is a spreading center in the Atlantic Ocean that separates the two continents.
Why must an aircraft be flying faster than sound to produce a shock wave and a sonic boom?
A duck swimming faster in water than water waves travel creates a bow wave. Similarly, a faster-than-sound aircraft creates a shock wave. The shock wave is the result of waves superimposing on one another. When the shock wave is incident upon a listener, a loud sound, the sonic boom, is produced. If the craft is moving at a speed less than the speed of sound, the waves don't overlap (superimpose). Then no shock wave and no sonic boom is produced.
How is light transmitted through glass?
According to the model of light presented in the text, when light is incident on a glass surface, each photon (particle of light) is absorbed by a glass molecule or atom. This forces the molecule or atom into vibration, which results in the emission of an indistinguishable photon, which travels to the next atom or molecule to repeat the process. A cascading process of absorption and reemission occurs until the molecule at the far surface absorbs and re-emits the photon.
How might you separate a mixture of sand and salt? How about a mixture of iron and sand?
Add the mixture of sand and salt to some water. Stir, and then filter the sand. Rinse the sand several times with fresh water to make sure that all of the salt has been removed. Collect all the salty water and evaporate away the water. The residue that remains will be the salt. After the sand dries, you've got just the sand. For a mixture of iron and sand, take advantage of the fact that only iron is attracted to a magnet.
Two plastic bottles of fresh seltzer water are opened. Three-fourths of the first bottle are poured out for drinking while none of the second bottle is poured out. Both bottles are then tightly resealed. The next day they are both re-opened but one is less fizzy. Which one? Why?
After resealing a bottle of seltzer water, the carbon dioxide will continue to come out of solution to fill the up the head space within the bottle. The larger the head space, the greater the amount of carbon dioxide that will come out. The bottle that is three-fourths empty has more head space to fill, but the reserve of dissolved carbon dioxide is less because it contains less seltzer water. The near empty bottle of seltzer water thus becomes quickly depleted of carbon dioxide, which leads to little fizz. Contrast this to the bottle that is full of seltzer water. Here there is only a small amount of head space to fill, but plenty of reserve.
Where were the atoms that compose our bodies "manufactured?"
All atoms heavier than hydrogen (and some helium) are the outcome of stellar processes. In the hot cauldrons of stars, atoms combine to transform hydrogen into elements up to iron in the periodic table. Atoms heaver than iron were made when huge stars underwent supernovae explosions. That's why we can truly say we're all made of stardust
What is the cause of a magnetic field about a permanent magnet? About a current-carrying wire? Are the causes for each different? Explain.
All magnetic fields have their origin in moving electric charges. In a permanent magnet, the moving charges are the electrons in the atoms making up the magnet—most commonly, iron atoms. In a current-carrying wire, the moving electrons produce the magnetic field. So the cause of magnetic fields about atoms and about wires with currents in them is the same.
Distinguish between a transverse wave and a longitudinal wave. Give examples of each.
All waves are vibrations in space and time. In a transverse wave the vibrations are perpendicular to the direction of wave travel. Vibrations in a longitudinal wave are along or parallel to the direction of wave travel. Transverse waves include those of a vibrating string, waves on water, and electromagnetic waves. Examples of longitudinal waves are sound, those in a to-and-fro vibrating spring toy, and some types of earthquake waves.
Describe the three main rays produced by radioactivity? Which will penetrate farther into material?
Alpha rays, beta rays, and gamma rays. Alpha rays are streams of particles, which are the nuclei of helium atoms. They are the heaviest particles ejected by radioactive materials, and are positively charged. Beta rays are streams of electrons, emanating from the nucleus, and are negatively charged. Gamma rays are high-frequency electromagnetic waves ejected by the atomic nucleus during decay. Gamma rays have no electric charge and are the most penetrating of the rays.
Distinguish between ac and dc. When you plug a lamp into a wall socket, where do the electrons come from?
Alternating current is ac, where electrons do not migrate but simply alternate about relatively fixed positions. In dc, the flow of electrons is in one direction only. Migration does occur, but the source of electrons, whether in a dc or ac circuit, is the electrical conductor itself. You can buy a water pipe in a hardware store with no water inside, but you can't buy an electric pipe (wire) without its store of electrons. Wires and all materials come with electrons in them (and as many protons, so they're not normally charged).
The majority of elements in the Periodic Table are metallic. Does this mean that most minerals are metallic?
Although the different metallic elements combine and give us minerals, not all minerals made up of metallic elements are considered metallic minerals. Properties of single elements are very different from the properties of the compounds of elements. For example, the elements Na and Cl combine to form the compound NaCl. Whereas elemental sodium is a soft silvery metal, and elemental chlorine is a toxic yellow-green gas, when the two elements are combined they form common table salt, NaCl (the mineral halite). And although composed of metallic elements, halite is not considered to be a metallic mineral.
The atoms in your body are mostly empty space. The floor that you stand on, from an atomic point of view, is also mostly empty space. So why don't you fall through the floor?
Although the spaces within atoms is mostly void, the space is not devoid of electrons whirling around in that space. Electrons repel other electrons, so when your foot presses on the floor, electric repulsion between the material of your foot and the floor keep your foot and floor from meshing into each other. Electrical repulsion keeps us from falling through the floor or other solid surfaces.
What is the difference between a mineral and an element?
An element is a material consisting of only one type of atom. Although a few minerals are composed of single elements, the majority of minerals are composed of a combination of elements. As such, they are composed of more than one type of atom.
How are glacial striations related to continental drift?
As a glacier moves over the land, it gouges the surface—this reveals the direction of ice flow. Glacial striations found in South America, southern Africa, India, and southern Australia provide evidence of an extensive ice sheet that existed about 300 million years ago. Such an extensive ice sheet would have made the world climate very cold. But in the Northern Hemisphere it was a time of subtropical climate. So Wegener proposed that the glaciated regions were located near the South Pole and the "modern" northern continents were located nearer to the tropics.
A skillet is lined with a thin layer of cooking oil followed by a layer of unpopped popcorn kernels. Upon heating the kernels all pop thereby escaping the skillet. Identify any physical or chemical changes.
As each kernel is heated, the water within each kernel is also heated to the point that it would turn into water vapor. The shell of the kernel, however, is air tight and this keeps the water as a superheated liquid. Eventually, the pressure exerted by the superheated water exceeds the holding power of the kernel and the water bursts out as a vapor, which causes the kernel to pop. These are physical changes. The starches within the kernel, however, are also cooked by the high temperatures, and this is an example of a chemical change.
How is it possible for a jet airplane carrying 110 tons of jet fuel to emit 340 tons of carbon dioxide?
As the carbon-based fuel combusts it gains mass as it combines with the oxygen from the atmosphere to form carbon dioxide, CO2 , which comes out in the exhaust.
Radiation from a point source obeys the inverse-square law. If a Geiger counter 1 meter from a small sample reads 360 counts per minute, what will be its counting rate at 2 meters from the source? At 3 meters from the source?
At 2 m the reading will be 1/4, 90 counts per minute. At 3 m the reading will be 1/9, 40 counts per minute.
If a sample of a radioactive isotope has a half-life of 1 year, how much of the original sample will be left at the end of the second year? At the end of the third year? At the end of the fourth year?
At the end of the second year 1/4 will remain. At the end of the third year 1/8 will remain. At the end of the fourth year 1/16 will remain.
Pour vinegar onto beach sand from the Caribbean and the result is a lot of froth and bubbles. Pour vinegar onto beach sand from California, however, and nothing happens. Why?
Beach sand from the Caribbean and many other tropical climates is made primarily of the calcium carbonate remains of coral and shelled creatures. Vinegar is an acid and the calcium carbonate is a base. The reaction between the two results in the formation of carbon dioxide, which creates bubbles as it is formed. California beach sand primarily comes from the erosion of rocks and minerals, which are mostly made of inert silicon dioxide, SiO2.
What are the similarities and differences between Newton's law of gravity and Coulomb's law?
Both laws are inverse-square laws and both are directly dependent on the quantities involved: electric charge for electrical force, and mass for gravitational force. The Coulomb force between a pair of electrons is many billions of times greater than the gravitational force between them. Whereas the gravitational force is only attractive, the Coulomb force can be attractive or repulsive, depending on the signs of charge.
Does a refrigerator prevent or delay the spoilage of food? Explain.
Chemical reactions, including those of a biological nature responsible for the spoilage of food, slow down with decreasing temperature. The refrigerator, therefore, only slows down (delays) the spoilage of food.
Describe the theory of continental drift.
Continental drift proposed that the continents are not stationary—they move. The theory was supported by the jig-saw fit of continental land masses at their margins, and by paleoclimate and paleontology evidence. Although the evidence was remarkable, it did not provide a suitable driving mechanism to produce such crustal movement
Describe the process of crystallization.
Crystallization is the growth of a solid from a material whose atoms come together with a specific chemical composition and crystalline arrangement. Beginning with the formation of a single microscopic crystal, the crystal grows as more and more atoms bond to the crystal faces.
Calculate the current where 10 coulombs of charge pass a point in 5 seconds.
Current = charge flow/time = (10 C)/(5s) = 2.0 A.
Which will do more damage, plugging a 120-V hair dryer into a 240-V circuit or plugging a 240-V hair dryer into a 120-V circuit? Explain.
Damage generally occurs from excess heating caused by too much current through an appliance. For an appliance that converts electrical energy directly to heat, such as a hair dryer, this occurs when excess voltage is applied. So don't connect a 120-V device to a 240-V circuit. (Interestingly, if the device is an electric motor, then applying too little voltage can result in the motor overheating and burning up the motor windings. But that's another story.)
Why is it sometimes difficult to decide whether an observed change is physical or chemical?
Determining whether a change is physical or chemical can be difficult because both involve changes in appearance.
Briefly describe the different types of plate boundaries
Divergent boundaries, produced by tensional stress, are areas of crustal formation. Convergent boundaries, produced by compressional stress, are areas of crustal destruction. Transform fault boundaries, produced by shear stress, are areas where plates slide past one another.
What are the eight major tectonic plates?
Eurasian Plate, Indo-Australian Plate, Pacific Plate, North American Plate, South American Plate, Nazca Plate, African Plate, and the Antarctic Plate.
State Faraday's law and explain what it means. Cite at least three applications.
Faraday's law states that voltage induced in a coil is proportional to the rate at which the magnetic field strength through the coil changes. It is also proportional to the number of turns of wire making up the coil and the strength of the changing magnetic field. Magnetic field change can be brought about by rotating a coil, changing its shape, or changing the magnetic field strength. Because of Faraday's law, current need not be restricted to batteries, but can be induced in a wire by any of the changes stated. Faraday's law underlies generators, metal detectors, tape recorders, microphones, transformers, and many familiar devices around us. Light itself, is the result of Faraday's law applied to electric and magnetic fields.
Most of the world's sand is made up of which two minerals?
Feldspar, the most common and abundant mineral, and quartz, the second most common mineral, make up most of the world's sand deposits.
Why does the fluorine atom tend to gain only one electron?
Fluorine only has room for one more electron in its outermost shell.
Distinguish between metamorphic foliation and sedimentary layering.
Foliation is the realignment of minerals during recrystallization so that they are perpendicular to the direction of compressive force. Sedimentary layering is the result of the laying down of sediments one on top of the other
If we double the frequency of light, we double the energy of each of its photons. If, instead, we double the wavelength of light, what happens to the photon energy?
For any wave, sound or light, longer wavelength corresponds to lower frequency. Doubled wavelength means half the frequency. So the photons in the longer-wavelength light have half the energy.
Calculate the resistance of the filament in a lamp that carries 0.4 A when 3.0 V is impressed across it.
From I = V/R, R = V/I = (3.0 V)/(0.4 A) = 7.5 .
What causes convection currents in the mantle?
Gravity and heat. When rock is heated it rises and expands—this makes it less dense. Then, closer to the surface, the rock cools and contracts—making it more dense. As gravity pulls the denser rock downward, the less dense rock continues to rise and takes the place of the sinking dense rock pulled downward by gravity—Convection!
Who was Harry H. Hess, and what was his role in supporting continental drift?
Harry Hess was a geology professor who also served as a naval officer during World War II. Hess proposed the theory of seafloor spreading—that in a conveyor type fashion, rising material from the mantle oozes upward at mid-ocean ridges to form new lithosphere and old lithosphere is simultaneously destroyed (recycled) in deep ocean trenches near the edges of continents. So Hess's seafloor spreading provided the driving mechanism to support continental drift.
With no one looking, you add 5 mL of a cinnamon solution to a blue balloon, which you tie shut. You also add 5 mL of fresh water to a red balloon, which you also tie shut. You heat the two balloons in a microwave until they each inflate to about the size of a grapefruit. Your brother then comes along, examines the inflated balloons and tells you that the blue balloon is the one containing the cinnamon. How did he know?
He could smell the cinnamon molecules as they readily leaked through the microscopic pores of the balloon
Calculate the current through a 12-ohm hair dryer connected to a 120-V power source.
I = V/R = (120V)/(12 ) = 10 A.
Calculate the current in the coiled heating element of a 240-V stove. The resistance of the element is 60 ohms at its operating temperature.
I = V/R = (120V)/(60 ) = 2 A.
Describe how the different paths of polar wandering helped establish that continents move over geologic time
If one were to plot the apparent path of polar wandering as determined from North American rocks it would look different than the path determined from European rocks. If one were to move North America and Europe back together, then the paths of polar wandering would overlie one another.
Take money away from your bank account and the bank will show a negative credit. Take an electron away from an atom, however, and the atom shows up positive. Explain.
In a neutral atom the number of negatively charged electrons is the same as the number of positively charged protons. Take away one of the negative electrons, however, then there will be an excess of positively charged protons.
How is suspended animation similar to death? How is it different?
In both suspended animation and death, the cells of the body are no longer working. Suspended animation is different from death, however, because the cells have the potential to start working again.
Why is the secondary rainbow dimmer than the primary rainbow?
In water drops making up a primary bow is an internal reflection of the light ray, which sends it toward the viewer. Not all of the light is internally reflected, however, as some refracts out of the drop. So the internally reflected light ray is less intense. In water drops making up a secondary bow there are two internal reflections. This results in further dimming, which is why the secondary bow is not as bright as the primary bow.
The isotope cesium-137, which has a half-life of 30 years, is a product of nuclear power plants. Show that it takes 120 years for this isotope to decay to about one-sixteenth its original amount.
It will take four half-lives to decrease to 1/16 the original amount. Four 30-year half-lives of cesium-137 = 120 years
Which would produce a more valued product, adding or removing protons from the element mercury? Defend your answer (with access to the periodic table).
Mercury (Hg) has atomic number 80. If a proton is added to the nucleus of a mercury atom, it becomes element 81, thallium (Tl). If, however, a proton is removed from the nucleus of a mercury atom, it becomes element 79. This is gold (Au), considerably more valuable than thallium.
Which type(s) of rock is (are) made from previously existing rock? Which type requires high temperature and/or pressure for its formation?
Metamorphic and sedimentary rock. Metamorphic rock requires high temperature and/or high pressure
Describe two sources from which minerals can crystallize.
Minerals crystallize from 1. magma—molten rock from Earth's interior, and from 2. water solutions—precipitation of minerals from chemical sediments.
Why are sunsets reddish-orange in color?
Molecules in the sky scatter light. The smaller the molecule, the more light of the higher frequencies is scattered. Oxygen and nitrogen molecules are small and best scatter the higher frequencies of light. That's why the sky is blue. The thickness of the atmosphere plays a role. For a very thick path, when much of the blue is scattered, light of the remaining lower frequencies pass through more readily. This occurs when the Sun is low on the horizon. The light path from the top of the atmosphere to the viewer is considerably longer. More blue is scattered, and what remains are the reds and oranges. Hence the reddish-orange sunset. The same occurs for the Moon, which is more reddish orange when close to the horizon than higher in the sky.
If uranium fissioned into three equal mass fragments instead of the usual two, would more or less energy be released in the fission reaction? (You may answer in terms of the mass/nucleon versus atomic number graphs in the book, Figures 16.19, 16.20, and 16.21.)
More energy would be released by a three-way split than the two-way split. The fragments would be smaller, have less mass than the usual fission fragments, and therefore be closer to iron in the mass per nucleon versus atomic number curve.
Where does most magma originate?
Most magma originates in Earth's interior from the partial melting of mantle rocks
What geologic features are explained by plate tectonics?
Mountain ranges, volcanoes, plutonic rocks, metamorphic rocks, folded and faulted rocks are all explained by plate tectonics. The deposition of marine sedimentary rocks on continental crust is explained by higher stands of sea level, which can often be attributed to faster seafloor spreading rates. Virtually all geologic processes can be tied back to plate tectonics.
How is the ocean floor like a gigantic slow-moving tape recorder?
New basalt extruded at an ocean ridge is magnetized according to the existing magnetic field. Alternating stripes of normal and reversed polarity on both sides of and parallel to the rift areas are like a very slow magnetic tape recording, showing the magnetic history of Earth and a continuous record of the movement of the seafloors
Consider a light bulb with this information printed on it: 100 W/120 V. Does this mean the bulb will consume 100 W of power connected to any amount of voltage? Explain.
No, the bulb will consume 100 W only if powered with 120 V. If it is powered with a greater voltage, it will consume more power; if it is powered with less voltage it will consume less power. (For example, if there is only 110 V across it, the power consumed will drop by more than 10 percent).
Is Earth's interior mostly magma?
No. Most of the Earth is actually solid, and the magma is derived from rocks that have melted.
If you look at your full-height image in a mirror, you barely see all of yourself. Then you move backward and you see that the image looks smaller because you're farther from the mirror. Does this mean that at greater distances a smaller mirror would show your full size? Explain.
No. The same size mirror will show your full image at any distance. That's because as you get farther away, not only does the mirror "shrink," but your image also "shrinks" in the same proportion. One has to try this to fully appreciate this fascinating fact!
Assuming the technique of suspended animation was safe, which it currently isn't, what would be some of the disadvantages to putting yourself under suspended animation for a long period of time?
Of course there is the cost associated with maintaining your body for all those years. But perhaps, more significant is that you would be saying good-bye to all your loved ones.
Why don't oil and water mix?
Oil and water do not mix because water molecules are more attracted to themselves than to oil molecules
Someone argues that he or she doesn't drink tap water because it contains thousands of molecules of some impurity in each glass. How would you respond in defense of the water's purity, if it indeed does contain thousands of molecules of some impurity per glass?
Only thousands of impurity molecules is incredibly small compared to the trillions of water molecules within this glass of water. Put it this way: for every one impurity molecule there would still be trillions more water molecules. This glass of water would be ULTRA pure
Calculate the power dissipated in a toaster that has a resistance of 14 ohms plugged into a 120-V outlet
P = IV = (V/R)V = V 2 /R = (120 V)2 /(14 ) = 1030 W
What is a major difference in the effect of wearing polarizing sunglasses versus glasses that simply cut down on intensity?
Polaroid sunglasses cut out glare. Much of the glare from surfaces is polarized in a plane matching that of the reflecting surface. Glare from water, for example, is horizontally polarized. Glasses with vertical polarization axes cut out this glare, whereas regular lenses don't discriminate between glare and bright light.
What happens to a current-carrying wire placed in a magnetic field? Explain.
Properly oriented, a current-carrying wire experiences a force when it is in a magnetic field. The force is proportional to the magnetic field strength and the current in the wire, and depends on the orientation of the wire. When the wire is perpendicular to the magnetic field, force is maximum. When the wire is parallel to the magnetic field, force is minimum—that is, zero. In between parallel and perpendicular, the force varies between minimum and maximum.
Many people hear about atmospheric ozone depletion and wonder why we don't simply replace that which has been destroyed. Knowing about chlorofluorocarbons and knowing how catalysts work, explain how this would not be a lasting solution.
Putting more ozone into the atmosphere to replace that which has been destroyed is a bit like throwing more fish into a pool of sharks to replace those fish that have been eaten. The solution is to remove the CFC's that destroy the ozone. Unfortunately, CFC only degrade slowly and the ones up there now will remain there for many years to come. Our best bet is to stop the present production of CFC's and hope that we haven't already caused too much damage.
Explain how radioactive decay has always warmed the Earth from the inside, and how nuclear fusion has always warmed Earth from the outside.
Radioactivity in Earth's interior is a main contributor to the thermal energy that keeps the interior molten and warms hot springs and geysers. Fusion in the Sun provides the energy that reaches us in sunlight
Describe seafloor spreading.
Seafloor spreading states that ocean basins spread apart as the ocean crust grows at the mid-ocean ridges.
What rock type is made up of previously existing rock whose formation does not involve high temperature and pressure?
Sedimentary rock when the previously existing rock is subjected to forces of weathering and erosion
What is the major rock-forming mineral group? Give examples of minerals in this group.
Silicates are the most abundant mineral group in Earth's crust. Feldspars, quartz, pyroxenes, amphiboles, and micas are examples of silicates.
What are the rock-forming mineral groups?
Silicates, carbonates, oxides, sulfides, and sulfates
How are plant and animal fossils related to the theory of continental drift?
Similar plant and animal fossils found in both South America and Africa provided evidence that the two continents had at one time been connected together.
How necessary is soap for removing salt from your hands? Why?
Soap is not at all necessary for removing salt from your hands. The strong ion-dipole interactions between fresh water and the salt are most sufficient to lift the salt away from your hands.
A skipper on a moored boat notices wave crests passing his anchor chain every 5 s. He estimates the distance between wave crests to be 15 m. He also correctly estimates the speed of the waves. Show that this speed is 3 m/s.
Speed = = = 3 m/s. Or in wave terminology: Speed = frequency wavelength = (1/5 Hz)(15 m) = 3 m/s.
How does wave speed relate to wave frequency? If the speed of a longitudinal wave is 340 m/s and the frequency is 1000 Hz, what is the wavelength of the wave?
Speed = wave frequency wavelength. So wavelength = speed frequency = 340 m/s 1000 Hz = 0.34 m.
Why are most earthquakes generated near plate boundaries?
Stress builds up in lithospheric plates where two (or three) plates touch—at their boundaries. When the stress reaches a critical threshold, rocks break, slide past one another, and generate earthquakes.
What is the connection, if any, between sunshine and electromagnetic induction?
Sunshine is light, which is part of the electromagnetic spectrum, all of which is produced by acceleration of electric charges—mainly electrons. Vibrating electrons in the Sun, or in any body, constitute changing electric currents, which induce changing magnetic fields, which induce changing electric fields and so on continuously. All light is composed of electromagnetic waves.
Which has the thicker lamp filament, a 60-W bulb or a 100-W bulb?
The 100-W bulb has less resistance and a thicker filament, resulting in more current. This is consistent with the power relationship P = IV. More current I for the same voltage V means less resistance.
What is the Doppler effect, and how is it produced? Cite an example
The Doppler effect is a perceived change in frequency produced by relative motion between a receiver and a wave source. If a wave source approaches a receiver, waves encounter the receiver more often and a higher frequency is perceived. If a wave source recedes, waves encounter a receiver less often and a lower frequency is perceived. In the case of sound, when an ambulance sounding its siren approaches you, its pitch is higher. And after it passes, moving away, its pitch is lower. In the case of light, the spin of a star can be determined by noting that one edge has a slightly different color (frequency of light) than the opposite edge.
Fish don't live very long in water that has been boiled and brought back to room temperature. Why?
The boiling process removes the air that was dissolved in the water. Upon cooling the water is void of its usual air content, hence, the fish drown.
Why is a water molecule more attracted to a calcium ion than a sodium ion?
The calcium ion, Ca 2+ , has a twice the positive charge. You might think, therefore, that water is attracted twice as much. Not so! The calcium ion is also larger, which means that the water cannot get so close to the source of this positive charge, which is the atomic nucleus.
Are the chemical reactions that take place in a disposable battery exothermic or endothermic? What evidence supports your answer? Is the reaction going on in a rechargeable battery while it is recharging exothermic or endothermic?
The chemical reactions within a disposable battery are exothermic as evidenced by the electrical energy they release. To recharge a rechargeable battery requires the input of electrical energy, hence, the reactions that proceed during the recharging process are endothermic.
What produces the beautiful colors seen in gasoline spilled on a wet street? How, for example, is yellow light produced?
The colors are produced by interference. Light that reflects from the upper gasoline surface interferes with light that reflects from the underlying water surface. When the distance between the two surfaces is very tiny—less than the wavelength of light—destructive interference results when one wave lags another of the same frequency by a half wavelength. When blue is cancelled, for example, the color that results is its complement, yellow
Are the present-day continents a permanent feature on our planet? How about the present-day ocean basins?
The continents are relatively permanent, but their present-day arrangement is not a permanent feature. Continents move. The oceans originated very early in Earth's history, but the present-day ocean basins are not a permanent feature. As continents move, ocean basins widen and shrink.
How does the current in a battery compare with the current in the circuit it is connected to? Explain
The current in the battery is the same as the current in the circuit it powers (assuming it is the only battery in the circuit). This is true whether the circuit is a series or parallel one. As more resistors are added to a series circuit, current in the battery (and circuit) is less because the total resistance is more. If the circuit is a simple parallel one, current in the battery (and circuit) is more because the equivalent resistance of the circuit is less.
A cotton ball dipped in alcohol is wiped across a table top. Would the resulting smell of the alcohol be more or less noticeable if the table top were much warmer? Explain
The greater warmth of the table top provides more energy for the alcohol molecules to go into the gaseous phase. The rate at which the alcohol evaporates would be greater. As a result there would be more alcohol molecules in the air more quickly, which would register in your nose as more noticeable.
How is energy released from nuclear fission and nuclear fusion, especially since they are opposite processes?
The name of the energy game is "lose mass." In both fission and fusion, mass is decreased in the reactions. But only light nuclei lose mass by fusion and only heavy nuclei lose mass by fission (fusing heavy nuclei and fissioning light nuclei would absorb rather than release energy). When uranium fissions, the masses of its fragments are less than the mass of the uranium nucleus. Similarly, when hydrogen nuclei fuse, the resulting helium nucleus has less mass than was had by the two hydrogens. The missing mass, multiplied by the speed of light squared, equals the amount of released energy. (This energy is carried in the kinetic energy of the fragments for fission, and in the kinetic energy of the neutrons and recoiling helium for fusion.)
Where on Earth do you think the oldest rocks would be found, on the continents or the deep ocean floor? Why?
The oldest rocks are more likely to be found on the continents. As we learned in this chapter, seafloor is constantly being formed at mid-ocean ridges (seafloor spreading) and destroyed at deep ocean trenches (subduction). We also learned that the less-dense continents resist subduction, even at plate boundaries. For these two reasons, rocks are more likely to survive for long periods of time on continents. Rocks on the seafloor are likely to be subducted and destroyed.
What are the three primary colors for light addition? What colors appear when light of only two primary colors are shone on a white screen?
The three primary colors are red, green, and blue. When two primary colors overlap, the result is the complementary color of the third primary color. When red and green overlap, for example, the color produced is the complement of blue—which is yellow. When red and blue overlap, the color produced is the complement of green—which is magenta.
How does sediment turn into sedimentary rock?
The transformation of sediments to sedimentary rock occurs in two ways—compaction and cementation. As overlying sediments press down on deeper layers, the sediment particles are squeezed and compacted together. Water squeezed out of the spaces between sediment particles often contains in solution compounds such as silica, calcite, and hematite that act as cementing agents.
An individual carbon-oxygen bond is polar. Yet carbon dioxide, CO2, which has two carbon-oxygen bonds, is nonpolar. Why?
The two oxygen atoms in carbon dioxide are 180 apart from each another such that their electron-pulls on the central carbon atom are equal and opposite. The two dipoles, therefore, balance each other out making carbon dioxide a nonpolar compound.
Which has the greatest energy, a photon of infrared light, a photon of visible light, or a photon of ultraviolet light? Defend your answer
The ultraviolet photon has more energy than the other two. This is in accord with the relationship, E ~ f, which states the energy of a photon is directly proportional to its frequency. Of the three, the ultraviolet photon has the highest frequency, and therefore, the greatest energy.
Why are some tennis balls, Ping-Pong balls, and fire engines yellow-green in color? Is there a physics explanation?
These objects are yellow-green for a reason. Light from the Sun spans a wide range of frequencies, as the solar radiation curve shows. The peak energy occurs in the frequency range of yellow-green. During the course of our evolution, we have matched our eyesight to this brightest of colors, and we see yellow-green as brighter than other colors. This is important in seeing fast-moving balls and fire engines. Physics is in everything we see
Describe two ways to tell whether a sugar solution is saturated or not.
To tell whether a sugar solution is saturated or not, add more sugar and see if it will dissolve. If the sugar dissolves, the solution was not saturated. Alternatively, cool the solution and see if any sugar precipitates. If it precipitates then the solution was saturated. Because sugar forms supersaturated solutions so easily, however, neither of these methods are always successful.
A sample of a particular radioisotope is placed near a Geiger counter, which is observed to register 160 counts per minute. Eight hours later, the detector counts at a rate of 10 counts per minute. What is the half-life of the material?
Two hours. (160cpm/2 = 80, 1 half-life; 80cpm/2 = 40, 2 half-lives; 40cpm/2 = 20, 3 half- lives; 20cpm/2 = 10, 4 half-lives. So 4 half-lives = 8 hours means a 2-hour half-life.)
Why is ultraviolet light not transmitted through glass?
Ultraviolet light is in the range of frequencies that resonate with atoms and molecules in the glass. At resonance, the amplitudes of vibration are very large and the energy degrades to thermal energy, rather than continuing as light. So glass is opaque to ultraviolet, but transparent to visible light.
Minerals in volcanic rocks are usually smaller than minerals in plutonic rock. Why is this?
Volcanic rocks form at Earth's surface. Plutonic rocks form beneath the Earth's surface. Because volcanic rock is extruded at the surface, it cools faster than plutonic rock. The shorter the cooling time, the smaller the crystals.
What is wave interference? Cite two types of wave interference.
Wave interference occurs when two or more waves combine. When they combine in phase—that is, with crests overlapping crests and troughs overlapping troughs—the resulting wave has greater amplitude. This is constructive interference. When overlapping is of crest on trough, cancellation or diminishing of the wave results. This is destructive interference.
From a scientific point of view, what does it mean when a scientist says that "we are all one?"
We are all one in the sense that the atoms that compose our bodies belong to all of us and to all things. Atoms cycle and recycle continuously. The atoms in your ear today may have been in your neighbor's finger a few days ago. In our bodies are atoms that once were a part of everyone who ever lived on Earth. And the atoms presently in our bodies will live in the bodies of people not yet born. In this sense, at least, we are truly all one
As we digest and subsequently metabolize food, is the food gradually oxidized or reduced? What evidence do you have?
We exhale carbon dioxide and water vapor, which are the products of the oxidation of the food we eat
What is the difference between sediments and sedimentary rock?
Weathering breaks rock down to produce sediment. Sediments are small pieces of rock. As the deposited sediment accumulates, it begins to change into sedimentary rock by compaction and cementation
Under what conditions will a hot pie not lose heat to its surroundings?
While the pie is still in the hot oven where the temperature of its surroundings are the same or greater.
Can a particle act like a wave? Can a wave act like a particle? Give examples.
Yes to both questions. Electrons protons, neutrons, and all matter have wave properties. This wave nature is seen when a beam of particles passes through thin passages and emerges in patterns. Particles directed through diffraction slits exhibit interference patterns similar to those of light. We say that light travels as a wave, but strikes like a particle.
A weight suspended from a spring is seen to bob up and down over a distance of 20 centimeters twice each second. What is its frequency? Its period? Its amplitude?
a. Frequency = 2 bobs/second = 2 hertz; b. Period = 1/f = 1/2 second; c. amplitude is distance from the equilibrium position to maximum displacement, one-half the 20-cm peak-to-peak distance or 10 cm (which decreases with time).
What is the frequency, in hertz, that corresponds to each of the following periods? a. 0.10 s b. 5 s c. 1/60 s
a. f = 1/T = 1/0.10 s = 10 Hz; b. f = 1/5 = 0.2 Hz; c. f = 1/(1/60 s) = 60 Hz
Show that the pH of a solution is 10 when the hydronium ion concentration of this solution is 1 10-10 mole per liter. Is the solution acidic or basic?
pH = - log [H3O+ ] = - log (10-10) = - (-10) = 10
