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the average of a set of values is also called the mode. | (A) true (B) false | B | The central tendency of a sample can be represented by the mean, median, or mode. The mean is the average value. It is calculated by adding the individual measurements and dividing the sum by the total number of measurements. The median is the middle value. To find the median, rank all the measurements from smallest to... |
the mode of the set of measurements in question 8 is | (A) 2435 cm (B) 2251 cm (C) 2343 cm (D) 2098 cm | D | The central tendency of a sample can be represented by the mean, median, or mode. The mean is the average value. It is calculated by adding the individual measurements and dividing the sum by the total number of measurements. The median is the middle value. To find the median, rank all the measurements from smallest to... |
terms used to describe relative direction include | (A) in (B) up (C) sideways (D) all of the above | D | Direction can be described in relative terms, such as up, down, in, out, left, right, forward, backward, or sideways. Direction can also be described with the cardinal directions: north, south, east, or west. On maps, cardinal directions are indicated with a compass rose. You can see one in the bottom left corner of th... |
the direction of motion is a vector. | (A) true (B) false | B | When both distance and direction are considered, motion can be represented by a vector. A vector is a measurement that has both size and direction. It may be represented by an arrow. If you are representing motion with an arrow, the length of the arrow represents distance, and the way the arrow points represents direct... |
if you are facing north, then east is to your | (A) left (B) right (C) back (D) none of the above | B | Direction is important if you want to go between two places. Directions are expressed as north (N), east (E), south (S), and west (W), with gradations in between. The most common way to describe direction in relation to the Earths surface is with a compass, a device with a floating needle that is actually a small magne... |
english units of distance include the | (A) mile (B) square mile (C) mile per hour (D) all of the above | A | The SI unit for distance is the meter (m). Short distances may be measured in centimeters (cm), and long distances may be measured in kilometers (km). For example, you might measure the distance from the bottom to the top of a sheet of paper in centimeters and the distance from your house to your school in kilometers. |
a millimeter is longer than a centimeter. | (A) true (B) false | B | Youve probably been using a ruler to measure length since you were in elementary school. But you may have made most of the measurements in English units of length, such as inches and feet. In science, length is most often measured in SI units, such as millimeters and centimeters. Many rulers have both types of units, o... |
a yard is closest in distance to a | (A) millimeter (B) centimeter (C) kilometer (D) meter | D | The SI unit for distance is the meter (m). Short distances may be measured in centimeters (cm), and long distances may be measured in kilometers (km). For example, you might measure the distance from the bottom to the top of a sheet of paper in centimeters and the distance from your house to your school in kilometers. |
to measure distance in si units, you could use a meter stick. | (A) true (B) false | A | The SI unit for distance is the meter (m). Short distances may be measured in centimeters (cm), and long distances may be measured in kilometers (km). For example, you might measure the distance from the bottom to the top of a sheet of paper in centimeters and the distance from your house to your school in kilometers. |
the doppler effect can occur when the | (A) sound source is moving and the listener is stationary (B) listener is moving and the sound source is stationary (C) sound source and listener are moving together (D) two of the above | D | The Doppler effect is a change in the frequency of sound waves that occurs when the source of the sound waves is moving relative to a stationary listener. (It can also occur when the sound source is stationary and the listener is moving.) The Figure 1.1 shows how the Doppler effect occurs. The sound waves from the poli... |
sound waves from a police car siren move away from the car in all directions. | (A) true (B) false | A | Look at the police car in Figure 20.6. The sound waves from its siren travel outward in all directions. Because the car is racing forward (toward the right), the sound waves get bunched up in front of the car and spread out behind it. As the car approaches the person on the right (position B), the sound waves get close... |
sound waves that are closer together have a lower frequency. | (A) true (B) false | B | How high or low a sound seems to a listener is its pitch. Pitch, in turn, depends on the frequency of sound waves. Wave frequency is the number of waves that pass a fixed point in a given amount of time. High-pitched sounds, like the sounds of the piccolo in the Figure 1.1, have high-frequency waves. Low-pitched sounds... |
as the frequency of sound waves gets lower, a listener perceives the sound to have a higher pitch. | (A) true (B) false | B | How high or low a sound seems to a listener is its pitch. Pitch, in turn, depends on the frequency of sound waves. Wave frequency is the number of waves that pass a fixed point in a given amount of time. High-pitched sounds, like the sounds of the piccolo in the Figure 1.1, have high-frequency waves. Low-pitched sounds... |
a police car is speeding north with its siren blaring. the sound waves from the siren increase in frequency | (A) north of the car (B) south of the car (C) in all directions around the car (D) none of the above | A | Look at the police car in Figure 20.6. The sound waves from its siren travel outward in all directions. Because the car is racing forward (toward the right), the sound waves get bunched up in front of the car and spread out behind it. As the car approaches the person on the right (position B), the sound waves get close... |
if you are standing a few blocks north of the police car in question 6, how does its siren sound to you as the car gets closer to your location? | (A) The siren’s pitch gets higher (B) The siren’s pitch gets lower (C) The siren’s pitch gets lower and then higher (D) The siren’s pitch does not change | A | As the car approaches listener A, the sound waves get closer together, increasing their frequency. This listener hears the pitch of the siren get higher. As the car speeds away from listener B, the sound waves get farther apart, decreasing their frequency. This listener hears the pitch of the siren get lower. Q: What w... |
after the police car in question 6 passes your location, how does the siren sound to you? | (A) The siren’s pitch gets higher (B) The siren’s pitch gets lower (C) The siren’s pitch gets lower and then higher (D) The siren’s pitch does not change | B | As the car approaches listener A, the sound waves get closer together, increasing their frequency. This listener hears the pitch of the siren get higher. As the car speeds away from listener B, the sound waves get farther apart, decreasing their frequency. This listener hears the pitch of the siren get lower. Q: What w... |
which shape of magnet does magnet earth resemble? | (A) horseshoe magnet (B) bar magnet (C) disc magnet (D) none of the above | B | Imagine a huge bar magnet passing through Earths axis, as illustrated in Figure 24.10. This is a good representation of Earth as a magnet. Like a bar magnet, Earth has north and south magnetic poles and a magnetic field. |
the place generally referred to as earths magnetic north pole is located closest to | (A) 90 degrees north latitude (B) 80 degrees north latitude (C) 70 degrees north latitude (D) 60 degrees north latitude | B | Like the real Earth, the globe pictured above is a magnet. A magnet is an object that has north and south magnetic poles and a magnetic field. The magnetic globe is a modern device, but the idea that Earth is a magnet is far from new. It was first proposed in 1600 by a British physician named William Gilbert. He used a... |
earth has two north poles and two south poles. | (A) true (B) false | A | All magnets have two magnetic poles. The poles are regions where the magnet is strongest. The poles are called north and south because they always line up with Earths north-south axis if the magnet is allowed to move freely. (Earths axis is the imaginary line around which the planet rotates.) What do you suppose would ... |
which of the following statements about earths magnetic field is false? | (A) It extends outward from Earth in all directions (B) It is strongest at the equator (C) Its lines of magnetic force converge at the poles (D) none of the above | B | Earth has a magnetic field (Figure 24.6). The magnetic field has north and south poles. The field extends several thousand kilometers into space. Earths magnetic field is created by the movements of molten metal in the outer core. Earths magnetic field shields us from harmful radiation from the Sun (Figure 24.7). If yo... |
a compass needle always points to earths geographic north pole. | (A) true (B) false | B | Although the needle of a compass always points north, it doesnt point to Earths north geographic pole. Find the north geographic pole in the Figure 1.2. As you can see, it is located at 90 north latitude. Where does a compass Q: The north end of a compass needle points toward Earths north magnetic pole. The like poles ... |
the like poles of two magnets always attract each other. | (A) true (B) false | B | All magnets have two magnetic poles. The poles are regions where the magnet is strongest. The poles are called north and south because they always line up with Earths north-south axis if the magnet is allowed to move freely. (Earths axis is the imaginary line around which the planet rotates.) What do you suppose would ... |
earths magnetic field is a huge region. | (A) true (B) false | A | Like all magnets, Earth has a magnetic field. Earths magnetic field is called the magnetosphere. It is a huge region that extends outward from Earth for several thousand kilometers but is strongest at the poles. You can see the extent of the magnetosphere in Figure 24.12. For an animated version of the magnetosphere, w... |
all machines make work easier. | (A) true (B) false | A | A machine is any device that makes work easier by changing a force. Work is done whenever a force moves an object over a distance. The amount of work done is represented by the equation: Work = Force x Distance When you use a machine, you apply force to the machine. This force is called the input force. The machine, in... |
you can get more work out of a machine than you put into it. | (A) true (B) false | B | You read above that machines do not increase the work done on an object. In other words, you cant get more work out of a machine than you put into it. In fact, machines always do less work on the object than the user does on the machine. Thats because all machines must use some of the work put into them to overcome fri... |
the percent of the work put into a machine (input work) that is actually used to do work (output work) is a measure of the machines | (A) power (B) efficiency (C) mechanical advantage (D) none of the above | B | You read above that machines do not increase the work done on an object. In other words, you cant get more work out of a machine than you put into it. In fact, machines always do less work on the object than the user does on the machine. Thats because all machines must use some of the work put into them to overcome fri... |
which equation is used to calculate the efficiency of a machine? | (A) Efficiency = Input Distance/Output Distance x 100% (B) Efficiency = Input Force/Output Force x 100% (C) Efficiency = Input Work/Output Work x 100% (D) none of the above | D | Efficiency can be calculated with the equation: Efficiency = Output work 100% Input work Consider a machine that puts out 6000 joules of work. To produce that much work from the machine requires the user to put in 8000 joules of work. To find the efficiency of the machine, substitute these values into the equation for ... |
newtons law of gravity was accepted for more than 200 years. | (A) true (B) false | A | People have known about gravity for thousands of years. After all, they constantly experienced gravity in their daily lives. They knew that things always fall toward the ground. However, it wasnt until Sir Isaac Newton developed his law of gravity in the late 1600s that people really began to understand gravity. Newton... |
newtons law of gravity explains why gravity occurs. | (A) true (B) false | B | In the late 1600s, Isaac Newton introduced his law of gravity, which identifies gravity as a force of attraction between all objects with mass in the universe. The law also states that the strength of gravity between two objects depends on their mass and distance apart. Newtons law of gravity was accepted for more than... |
einsteins concept of gravity involves | (A) mass (B) space (C) time (D) all of the above | D | In the early 1900s, Albert Einstein came up with a theory of gravity that actually explains gravity rather than simply describing its effects. Einstein showed mathematically that gravity is not really a force that of attraction between all objects with mass, as Newton thought. Instead, Einstein showed that gravity is a... |
einstein explained gravity with his theory of universal gravitation. | (A) true (B) false | B | In the early 1900s, Albert Einstein came up with a theory of gravity that actually explains gravity rather than simply describing its effects. Einstein showed mathematically that gravity is not really a force that of attraction between all objects with mass, as Newton thought. Instead, Einstein showed that gravity is a... |
einstein developed his theory about gravity by using | (A) evidence (B) observations (C) mathematics (D) scientific laws | C | In the early 1900s, Albert Einstein came up with a theory of gravity that actually explains gravity rather than simply describing its effects. Einstein showed mathematically that gravity is not really a force that of attraction between all objects with mass, as Newton thought. Instead, Einstein showed that gravity is a... |
einsteins concept of gravity is similar to what happens when you place a bowling ball on the surface of a trampoline. in this analogy, if the bowling ball represents earth, then the surface of the trampoline represents | (A) space-time (B) Earth’s gravity (C) Earth’s mass (D) none of the above | A | Einstein derived his theory using mathematics. However, you can get a good grasp of it with the help of a simple visual analogy. Imagine a bowling ball pressing down on a trampoline. The surface of the trampoline would curve downward instead of being flat. Now imagine placing a lighter ball at the edge of the trampolin... |
the less an elastic material is stretched or compressed, the greater the force it exerts. | (A) true (B) false | B | Something that is elastic can return to its original shape after being stretched or compressed. This property is called elasticity. As you stretch or compress an elastic material, it resists the change in shape. It exerts a counter force in the opposite direction. This force is called elastic force. Elastic force cause... |
elastic force causes an elastic material to spring back to its original shape after being stretched or compressed. | (A) true (B) false | A | Something that is elastic can return to its original shape after being stretched or compressed. This property is called elasticity. As you stretch or compress an elastic material, it resists the change in shape. It exerts a counter force in the opposite direction. This force is called elastic force. Elastic force cause... |
play objects with elasticity include | (A) spring toys (B) silly putty (C) modeling clay (D) all of the above | A | Potential energy due to an objects shape is called elastic potential energy. This energy results when elastic objects are stretched or compressed. Their elasticity gives them the potential to return to their original shape. For example, the rubber band in Figure 17.6 has been stretched, but it will spring back to its o... |
an elastic material offers no resistance to forces that change its shape. | (A) true (B) false | B | Something that is elastic can return to its original shape after being stretched or compressed. This property is called elasticity. As you stretch or compress an elastic material, it resists the change in shape. It exerts a counter force in the opposite direction. This force is called elastic force. Elastic force cause... |
most of the electromagnetic radiation on earth comes from the sun. | (A) true (B) false | A | Most of the energy that reaches the Earths surface comes from the Sun (Figure 1.1). About 44% of solar radiation is in the visible light wavelengths, but the Sun also emits infrared, ultraviolet, and other wavelengths. |
electromagnetic waves with longer wavelengths have | (A) higher frequencies (B) more energy (C) faster speeds (D) none of the above | D | Radio waves are the broad range of electromagnetic waves with the longest wavelengths and lowest frequencies. In Figure 21.7, you can see that the wavelength of radio waves may be longer than a soccer field. With their low frequencies, radio waves have the least energy of electromagnetic waves, but they still are extre... |
electromagnetic waves with the longest wavelengths are | (A) gamma rays (B) X rays (C) infrared light (D) radio waves | D | Electromagnetic waves on the left side of the Figure 1.1 are called radio waves. Radio waves are electromagnetic waves with the longest wavelengths. They may have wavelengths longer than a soccer field. They are also the electromagnetic waves with the lowest frequencies. With their low frequencies, they have the least ... |
electromagnetic waves with the greatest amount of energy are | (A) microwaves (B) ultraviolet light (C) infrared light (D) gamma rays | D | As you can see in the Figure 1.1, gamma rays have the shortest wavelengths and highest frequencies of all electromagnetic waves. Their wavelengths are shorter than the diameter of atomic nuclei, and their frequencies are greater than 1019 hertz (Hz). Thats 10 quadrillion waves per second! Because of their high frequenc... |
the frequencies of electromagnetic waves range from | (A) 104 to 1020 waves/second (B) 108 to 1016 waves/second (C) 1010 to 1014 waves/second (D) none of the above | A | Although all electromagnetic waves travel at the same speed across space, they may differ in their wavelengths, frequencies, and energy levels. Wavelength is the distance between corresponding points of adjacent waves (see the Figure 1.1). Wavelengths of electromagnetic waves range from longer than a soccer field to sh... |
the only electromagnetic waves in sunlight are ultraviolet, infrared, and visible light. | (A) true (B) false | B | Energy from the Sun has a wide range of wavelengths. The total range of energy is called the electromagnetic spectrum. You can see it in Figure 15.8. Visible light is the only light that humans can see. Different wavelengths of visible light appear as different colors. Radio waves have the longest wavelengths. They als... |
ultraviolet light has more energy than visible light. | (A) true (B) false | A | Energy from the Sun has a wide range of wavelengths. The total range of energy is called the electromagnetic spectrum. You can see it in Figure 15.8. Visible light is the only light that humans can see. Different wavelengths of visible light appear as different colors. Radio waves have the longest wavelengths. They als... |
electromagnetic waves need a medium in order to transfer energy. | (A) true (B) false | B | Unlike a mechanical transverse wave, which requires a medium, an electromagnetic transverse wave can travel through space without a medium. Waves traveling through a medium lose some energy to the medium. However, when an electromagnetic wave travels through space, no energy is lost, so the wave doesnt get weaker as it... |
electromagnetic waves | (A) create force fields (B) exert force over a distance (C) can travel through outer space (D) all of the above | D | Electromagnetic waves are waves that carry energy through matter or space as vibrating electric and magnetic fields. Electromagnetic waves have a wide range of wavelengths and frequencies. Sunlight contains the complete range of wavelengths of electromagnetic waves, which is called the electromagnetic spectrum. The Fig... |
electromagnetic waves are | (A) surface waves (B) transverse waves (C) longitudinal waves (D) none of the above | B | Electromagnetic waves are waves that carry energy through matter or space as vibrating electric and magnetic fields. Electromagnetic waves have a wide range of wavelengths and frequencies. Sunlight contains the complete range of wavelengths of electromagnetic waves, which is called the electromagnetic spectrum. The Fig... |
when electromagnetic waves strike matter they may be | (A) absorbed (B) reflected (C) refracted (D) any of the above | D | When electromagnetic waves strike matter, they may interact with it in the same ways that mechanical waves interact with matter. Electromagnetic waves may: reflect, or bounce back from a surface; refract, or bend when entering a new medium; diffract, or spread out around obstacles. Electromagnetic waves may also be abs... |
electromagnetic waves may be converted to other forms of energy. | (A) true (B) false | A | Electromagnetic waves can travel through matter as well as across space. When they strike matter, they interact with it in the same ways that mechanical waves interact with matter. They may reflect (bounce back), refract (bend when traveling through different materials), or diffract (bend around objects). They may also... |
orbitals may be shaped like | (A) spheres (B) dumbbells (C) rings (D) all of the above | D | The atomic model above is useful for some purposes, but its too simple when it comes to the location of electrons. In reality, its impossible to say what path an electron will follow. Instead, its only possible to describe the chances of finding an electron in a certain region around the nucleus. The region where an el... |
the atomic nucleus is always at the center of an orbital. | (A) true (B) false | A | The atomic model above is useful for some purposes, but its too simple when it comes to the location of electrons. In reality, its impossible to say what path an electron will follow. Instead, its only possible to describe the chances of finding an electron in a certain region around the nucleus. The region where an el... |
schroedinger thought that electrons | (A) are restricted to very specific orbits (B) might travel in waves like light (C) have very precise locations (D) behave like protons and neutrons | B | In the mid-1920s, an Austrian scientist named Erwin Schrdinger thought that the problem with Bohrs model was restricting the electrons to specific orbits. He wondered if electrons might behave like light, which scientists already knew had properties of both particles and waves. Schrdinger speculated that electrons migh... |
bohrs atomic model explains all of the behaviors of electrons in atoms of all elements. | (A) true (B) false | B | Up until about 1920, scientists accepted Niels Bohrs model of the atom. In this model, negative electrons circle the positive nucleus at fixed distances from the nucleus, called energy levels. You can see the model in Figure 1.1 for an atom of the element nitrogen. Bohrs model is useful for understanding properties of ... |
the electron cloud model of the atom is no longer accepted by most scientists. | (A) true (B) false | B | Today, these ideas about electrons are represented by the electron cloud model. The electron cloud is an area around the nucleus where electrons are likely to be. Figure 5.17 shows an electron cloud model for a helium atom. |
like protons and neutrons, electrons consist of smaller particles. | (A) true (B) false | B | Although atoms are very tiny, they consist of even smaller particles. Atoms are made of protons, neutrons, and electrons: Protons have a positive charge. Electrons have a negative charge. Neutrons are neutral in charge. |
an electron has an electrical charge of | (A) +1 (B) -1 (C) 0 (D) 0 or -1 | B | An electron is a particle outside the nucleus of an atom that has a negative electric charge. The charge of an electron is opposite but equal to the charge of a proton. Atoms have the same number of electrons as protons. As a result, the negative and positive charges "cancel out." This makes atoms electrically neutral.... |
an electron has about the same mass as a proton. | (A) true (B) false | B | Electrons are extremely small. The mass of an electron is only about 1/2000 the mass of a proton or neutron, so electrons contribute virtually nothing to the total mass of an atom. Electrons have an electric charge of -1, which is equal but opposite to the charge of proton, which is +1. All atoms have the same number o... |
atoms always have the same number of electrons as protons. | (A) true (B) false | A | The number of protons per atom is always the same for a given element. However, the number of neutrons may vary, and the number of electrons can change. |
what is the maximum number of electrons each orbital can hold? | (A) 1 (B) 2 (C) 4 (D) 8 | B | The smallest atoms are hydrogen atoms. They have just one electron orbiting the nucleus. That one electron is in the first energy level. Bigger atoms have more electrons. Electrons are always added to the lowest energy level first until it has the maximum number of electrons possible. Then electrons are added to the ne... |
no two elements are exactly alike. | (A) true (B) false | A | Every organism is different from every other organism. Every organisms genes are different, too. |
which of the following substances is not an element? | (A) oxygen (B) water (C) nitrogen (D) hydrogen | B | A pure substance is called an element. An element is a pure substance because it cannot be separated into any other substances. Currently, 92 different elements are known to exist in nature, although additional elements have been formed in labs. All matter consists of one or more of these elements. Some elements are ve... |
which element is attracted by a magnet? | (A) silver (B) aluminum (C) lead (D) iron | D | A magnet is an object that attracts certain materials such as iron. Youre probably familiar with common bar magnets, like the one in Figure 24.2. Like all magnets, this bar magnet has north and south poles and attracts objects such as paper clips that contain iron. |
which element glows red when electricity flows through it? | (A) iron (B) mercury (C) neon (D) copper | C | Think about the coil of an electric stove as it heats up. The coil changes in color as its temperature rises. When you first turn on the heat, the coil looks black. The air a few inches above the coil begins to feel warm. As the coil gets hotter, it starts to glow a dull red. As it gets even hotter, it becomes a bright... |
carbon is the most common element in living things. | (A) true (B) false | A | Carbon is a very important element to living things. As the second most common element in the human body, we know that human life without carbon would not be possible. Protein, carbohydrates, and fats are all part of the body and all contain carbon. When your body breaks down food to produce energy, you break down prot... |
aristotle correctly identified four of the elements. | (A) true (B) false | B | For thousands of years, people have wondered about the substances that make up matter. About 2500 years ago, the Greek philosopher Aristotle argued that all matter is made up of just four elements, which he identified as earth, air, water, and fire. He thought that different substances vary in their properties because ... |
the smallest particle of an element is a(n) | (A) molecule (B) crystal (C) compound (D) atom | D | The smallest particle of an element that still has the elements properties is an atom. All the atoms of an element are alike, and they are different from the atoms of all other elements. For example, atoms of gold are the same whether they are found in a gold nugget or a gold ring (see Figure 3.8). All gold atoms have ... |
only endothermic chemical reactions involve energy. | (A) true (B) false | B | All chemical reactions involve energy. Energy is used to break bonds in reactants, and energy is released when new bonds form in products. In some chemical reactions, called endothermic reactions, less energy is released when new bonds form in the products than is needed to break bonds in the reactants. The opposite is... |
in an endothermic reaction, it takes less energy to break bonds in the reactants than is released when new bonds form in the products. | (A) true (B) false | B | All chemical reactions involve energy. Energy is used to break bonds in reactants, and energy is released when new bonds form in products. In some chemical reactions, called endothermic reactions, less energy is released when new bonds form in the products than is needed to break bonds in the reactants. The opposite is... |
a constant input of energy is needed to keep an endothermic reaction going. | (A) true (B) false | A | The word endothermic literally means taking in heat. A constant input of energy, often in the form of heat, is needed to keep an endothermic reaction going. This is illustrated in the Figure 1.1. Energy must be constantly added because not enough energy is released when the products form to break more bonds in the reac... |
which statement about the chemical reactions of photosynthesis is true? | (A) They are endothermic (B) They produce energy in the form of light (C) They can be represented by 6CO2 + 6H2O → C6H12O6 + 6O2 (D) two of the above | D | Some of the most important biochemical reactions are the reactions involved in photosynthesis and cellular respira- tion. Together, these two processes provide energy to almost all of Earths organisms. The two processes are closely related, as you can see in the Figure 1.1. In photosynthesis, light energy from the sun ... |
during an endothermic reaction, energy is | (A) absorbed (B) released (C) destroyed (D) created | A | Whether a reaction absorbs energy or releases energy, there is no overall change in the amount of energy. Energy cannot be created or destroyed. This is the law of conservation of energy. Energy can change form for example, from electricity to light but the same amount of energy always remains. If energy cannot be dest... |
when work is done, energy is transferred from one object to another. | (A) true (B) false | A | Energy is defined in science as the ability to move matter or change matter in some other way. Energy can also be defined as the ability to do work, which means using force to move an object over a distance. When work is done, energy is transferred from one object to another. For example, when the boy in the Figure 1.1... |
the si unit for energy is the newton. | (A) true (B) false | B | Because energy is the ability to do work, it is expressed in the same unit that is used for work. The SI unit for both work and energy is the joule (J), or Newton meter (N m). One joule is the amount of energy needed to apply a force of 1 Newton over a distance of 1 meter. For example, suppose the boy in the Figure 1... |
forms of energy include | (A) chemical energy (B) mechanical energy (C) thermal energy (D) all of the above | D | Energy, or the ability to cause changes in matter, can exist in many different forms. Energy can also change from one form to another. The photo above of the guitar player represents six forms of energy: mechanical, chemical, electrical, light, thermal, and sound energy. Another form of energy is nuclear energy. Q: Can... |
anything that is moving has kinetic energy. | (A) true (B) false | A | Kinetic energy is the energy of moving matter. Anything that is moving has kinetic energyfrom atoms in matter to stars in outer space. Things with kinetic energy can do work. For example, the spinning saw blade in the photo above is doing the work of cutting through a piece of metal. |
when you run around a track, which type of energy are you demonstrating? | (A) mechanical energy (B) potential energy (C) kinetic energy (D) two of the above | D | There are many other examples of energy conversions between potential and kinetic energy. Figure 17.7 describes how potential energy changes to kinetic energy and back again on swings and trampolines. You can see an animation of changes between potential and kinetic energy on a ramp at the URL below. Can you think of o... |
energy conversion means saving energy. | (A) true (B) false | B | Everyone can reduce their use of energy resources and the pollution the resources cause by conserving energy. Conservation means saving resources by using them more efficiently, using less of them, or not using them at all. You can read below about some of the ways you can conserve energy on the road and in the home. |
most electricity comes from the burning of | (A) fossil fuels (B) trash (C) wood (D) none of the above | A | Around the world, coal is the largest source of energy for electricity. The United States is rich in coal (Figure 1.3). California once had a number of small coal mines, but the state no longer produces coal. To turn coal into electricity, the rock is crushed into powder, which is then burned in a furnace that has a bo... |
any form of energy can change into any other form of energy. | (A) true (B) false | A | Energy often changes from one form to another. For example, the mechanical energy of a moving drumstick changes to sound energy when it strikes the drumhead and causes it to vibrate. Any form of energy can change into any other form. Frequently, one form of energy changes into two or more different forms. For example, ... |
one form of energy can change into two or more other forms of energy. | (A) true (B) false | A | Energy often changes from one form to another. For example, the mechanical energy of a moving drumstick changes to sound energy when it strikes the drumhead and causes it to vibrate. Any form of energy can change into any other form. Frequently, one form of energy changes into two or more different forms. For example, ... |
examples of the energy conversion described in question 8 include | (A) using a playground slide (B) going up and down stairs (C) bouncing on a trampoline (D) all of the above | D | There are many other examples of energy conversions between potential and kinetic energy. Figure 17.7 describes how potential energy changes to kinetic energy and back again on swings and trampolines. You can see an animation of changes between potential and kinetic energy on a ramp at the URL below. Can you think of o... |
electrons can occupy the spaces between energy levels. | (A) true (B) false | B | Basic to Bohrs model is the idea of energy levels. Energy levels are areas located at fixed distances from the nucleus of the atom. They are the only places where electrons can be found. Energy levels are a little like rungs on a ladder. You can stand on one rung or another but not between the rungs. The same goes for ... |
electrons in the first energy level have the least amount of energy. | (A) true (B) false | A | Energy levels (also called electron shells) are fixed distances from the nucleus of an atom where electrons may be found. Electrons are tiny, negatively charged particles in an atom that move around the positive nucleus at the center. Energy levels are a little like the steps of a staircase. You can stand on one step o... |
if an atom has just three electrons, they will be located in energy level(s) | (A) I and II (B) I (C) II (D) and III (E) c I only (F) d I or II | A | Electrons are located at fixed distances from the nucleus, called energy levels. You can see the first three energy levels in the Figure 1.3. The diagram also shows the maximum possible number of electrons at each energy level. Electrons at lower energy levels, which are closer to the nucleus, have less energy. At the ... |
how many electrons can each orbital hold? | (A) 1 (B) 2 (C) 3 (D) 4 | B | The smallest atoms are hydrogen atoms. They have just one electron orbiting the nucleus. That one electron is in the first energy level. Bigger atoms have more electrons. Electrons are always added to the lowest energy level first until it has the maximum number of electrons possible. Then electrons are added to the ne... |
any atom is most stable when its outermost energy level contains | (A) a maximum of two electrons (B) a total of eight electrons (C) as many electrons as it can hold (D) fewer electrons than it can hold | C | Electrons in the outermost energy level of an atom have a special significance. These electrons are called valence electrons, and they determine many of the properties of an atom. An atom is most stable if its outermost energy level contains as many electrons as it can hold. For example, helium has two electrons, both ... |
valence electrons determine how reactive an element is. | (A) true (B) false | A | Valence electrons are the electrons in the outer energy level of an atom that can participate in interactions with other atoms. Valence electrons are generally the electrons that are farthest from the nucleus. As a result, they may be attracted as much or more by the nucleus of another atom than they are by their own n... |
enzymes work by providing activation energy. | (A) true (B) false | B | Enzymes are proteins that increase the rate of chemical reactions by reducing the amount of activation energy needed for reactants to start reacting. Enzymes are synthesized in the cells that need them, based on instructions encoded in the cells DNA. Enzymes arent changed or used up in the reactions they catalyze, so t... |
enzymes are used up in the reactions they catalyze. | (A) true (B) false | B | Enzymes are proteins that increase the rate of chemical reactions by reducing the amount of activation energy needed for reactants to start reacting. Enzymes are synthesized in the cells that need them, based on instructions encoded in the cells DNA. Enzymes arent changed or used up in the reactions they catalyze, so t... |
a human enzyme that helps digest starch is | (A) pepsase (B) starchase (C) amylase (D) glucase | C | Chemical reactions constantly occur inside living things. Many of these reactions require catalysts so they will occur quickly enough to support life. Catalysts in living things are called enzymes. Enzymes may be extremely effective. A reaction that takes a split second to occur with an enzyme might take many years wit... |
which of the following statements about enzymes if false? | (A) Enzymes are highly specialized for the reactions they catalyze (B) Enzymes are very effective at speeding up reactions (C) Enzymes are very efficient at catalyzing reactions (D) Enzymes usually result in the formation of waste products | D | Enzymes are proteins that increase the rate of chemical reactions by reducing the amount of activation energy needed for reactants to start reacting. Enzymes are synthesized in the cells that need them, based on instructions encoded in the cells DNA. Enzymes arent changed or used up in the reactions they catalyze, so t... |
about 100 different enzymes are needed for human life. | (A) true (B) false | B | More than 1000 different enzymes are necessary for human life. Many enzymes are needed for the digestion of food. Two examples are amylase and pepsin. Both are described in the Figure 1.2. |
enzymes are | (A) proteins (B) encoded in DNA (C) made in the cells where they are needed (D) all of the above | D | Enzymes are proteins that increase the rate of chemical reactions by reducing the amount of activation energy needed for reactants to start reacting. Enzymes are synthesized in the cells that need them, based on instructions encoded in the cells DNA. Enzymes arent changed or used up in the reactions they catalyze, so t... |
in an exothermic reaction, the reactants have more stored chemical energy than the products. | (A) true (B) false | A | All chemical reactions involve energy. Energy is used to break bonds in reactants, and energy is released when new bonds form in products. In some chemical reactions, called exothermic reactions, more energy is released when new bonds form in the products than is needed to break bonds in the reactants. The opposite is ... |
in an exothermic reaction, it takes more energy to break bonds in the reactants than is released when new bonds form in the products. | (A) true (B) false | B | All chemical reactions involve energy. Energy is used to break bonds in reactants, and energy is released when new bonds form in products. In some chemical reactions, called exothermic reactions, more energy is released when new bonds form in the products than is needed to break bonds in the reactants. The opposite is ... |
all combustion reactions are exothermic reactions. | (A) true (B) false | A | All combustion reactions are exothermic reactions. During a combustion reaction, a substance burns as it combines with oxygen. When substances burn, they usually give off energy as heat and light. Look at the big bonfire in the Figure 1.2. The combustion of wood is an exothermic reaction that releases a lot of energy a... |
which of the following reactions is exothermic? | (A) CH4 + F2 → CH3F + HF (B) CH4 + 2O2 → CO2 + 2H2O (C) 2H2O → 2H2 + O2 (D) two of the above | D | All chemical reactions involve energy. Energy is used to break bonds in reactants, and energy is released when new bonds form in products. In terms of energy, there are two types of chemical reactions: endothermic reactions and exothermic reactions. In exothermic reactions, more energy is released when bonds form in pr... |
a steam engine is an external combustion engine. | (A) true (B) false | A | An external combustion engine burns fuel externally, or outside the engine. The burning fuel releases thermal energy that is used to turn water to steam. The pressure of the steam is then used to move a piston back and forth in a cylinder. The kinetic energy of the moving piston can be used to turn a turbine or other d... |
an external combustion engine | (A) burns fuel outside the engine (B) changes kinetic energy to thermal energy (C) runs on electricity (D) all of the above | A | An external combustion engine burns fuel externally, or outside the engine. The burning fuel releases thermal energy that is used to turn water to steam. The pressure of the steam is then used to move a piston back and forth in a cylinder. The kinetic energy of the moving piston can be used to turn a turbine or other d... |
the kinetic energy of an external combustion engine can be used to | (A) turn the wheels of a vehicle (B) turn a turbine (C) run other machines (D) all of the above | D | An external combustion engine burns fuel externally, or outside the engine. The burning fuel releases thermal energy, which is used to heat water and change it to steam. The pressure of the steam moves a piston back and forth inside a cylinder. The kinetic energy of the moving piston can be used to turn a vehicles whee... |
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