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Physics, Chapter 7: Work And Energy, Henry Semat, Robert Katz
Physics, Chapter 7: Work And Energy, Henry Semat, Robert Katz
Robert Katz Publications
An extremely important concept that has been developed in physics is that of the work done on a body by the action of some external agent which exerts a force on this body and produces motion. For example, whenever someone lifts a body, he does work by exerting a force upward on it and moving it upward. Whenever a steam locomotive pulls a train, a series of processes takes place in the steam engine of the locomotive which enables it to exert a force on the train and move it in the direction of the force. The term work, as …
Physics, Contents, Henry Semat, Robert Katz
Physics, Contents, Henry Semat, Robert Katz
Robert Katz Publications
Table of contents
Physics, Chapter 30: Magnetic Fields Of Currents, Henry Semat, Robert Katz
Physics, Chapter 30: Magnetic Fields Of Currents, Henry Semat, Robert Katz
Robert Katz Publications
The first evidence for the existence of a magnetic field around an electric current was observed in 1820 by Hans Christian Oersted (1777-1851). He found that a wire carrying current caused a freely pivoted compass needle in its vicinity to be deflected. If the current in a long straight wire is directed from C to D, as shown in Figure 30-1, a compass needle below it, whose initial orientation is shown in dotted lines, will have its north pole deflected to the left and its south pole deflected to the right. If the current in the wire is reversed and …
Physics, Chapter 13: Properties Of Matter, Henry Semat, Robert Katz
Physics, Chapter 13: Properties Of Matter, Henry Semat, Robert Katz
Robert Katz Publications
When a system is subjected to external forces, it generally undergoes a change in size or shape or both. We have thus far touched very lightly on such changes; for example, we have considered the change in length of an elastic spring and the change in volume of a gas when such systems were subjected to varying pressures. The changes produced in a system by the action of external forces depend upon the physical properties of the material of which the system is composed. A study of the properties of matter leads to information which is of practical value to …
Physics, Chapter 1: Fundamental Quantities, Henry Semat, Robert Katz
Physics, Chapter 1: Fundamental Quantities, Henry Semat, Robert Katz
Robert Katz Publications
Physics is a fundamental science dealing with matter and energy. By convention, the subject matter of physics has been divided into such topics as mechanics, heat, sound, light, and electricity. In addition to these general classifications, present-day physics includes atomic physics, nuclear physics, solid-state physics, chemical physics, biophysics, and many other subdivisions. It is impossible to include all aspects of physics in a single definition or paragraph, and to distinguish physics clearly from its nearest neighbors, the other physical sciences-astronomy., chemistry, and geology.
Physics, Chapter 14: Temperature, Henry Semat, Robert Katz
Physics, Chapter 14: Temperature, Henry Semat, Robert Katz
Robert Katz Publications
Temperature is one of the fundamental concepts of physics. We are all able to recognize that some bodies are hotter than others, but our temperature sense is qualitative rather than quantitative and is capable of only a limited range. The sense of touch can frequently be used to distinguish between hotter and colder objects, provided that these lie in a temperature range consistent with the stability of human tissue. Even within this range the sense of touch is often unreliable as a measure of temperature.
The metal bracket holding a wooden rail may feel much colder to the touch than …
Physics, Chapter 5: Force And Motion, Henry Semat, Robert Katz
Physics, Chapter 5: Force And Motion, Henry Semat, Robert Katz
Robert Katz Publications
All of us have many times had the experience of setting a body in motion. If we analyze any of these experiences, we readily recall that in each case some force was required to start the object moving. In throwing a ball, moving a piece of furniture, or pulling a sled, the force needed to start the object moving is supplied by one's muscular effort as a push or a pull. In more complex cases, such as setting a car or an airplane in motion, the analysis, although more complicated, will also show that a force is required to start …
Physics, Preface, Henry Semat, Robert Katz
Physics, Preface, Henry Semat, Robert Katz
Robert Katz Publications
This book is intended for students of science and engineering; it aims to develop both an understanding of the important concepts of physics and some analytical skill in the solutions of problems. The mathematical level of the book is such that it may be used by students who are taking a course in calculus concurrently.
The notations and methods of the calculus are introduced early in the text, beginning with the concept of a derivative in the discussion of motion, and are then extended to more complex problems as the student progresses both in physics and in mathematics. Vector algebra …
Physics, Chapter 8: Hydrostatics (Fluids At Rest), Henry Semat, Robert Katz
Physics, Chapter 8: Hydrostatics (Fluids At Rest), Henry Semat, Robert Katz
Robert Katz Publications
From our everyday experience, we have become familiar with the fact that matter occurs in three different forms-solid, liquid, and gas. Under ordinary conditions stone, iron, copper, and chalk, for example, are solids; water, oil, and mercury are liquids; air, hydrogen, and carbon dioxide are gases. Each one of these forms is called a phase. At times it is difficult to distinguish clearly between the solid and the liquid phases, as in a material such as tar which flows under the action of a force at ordinary temperatures. Metals at high temperatures flow or "creep" under the action of a …
Physics, Chapter 3: The Equilibrium Of A Particle, Henry Semat, Robert Katz
Physics, Chapter 3: The Equilibrium Of A Particle, Henry Semat, Robert Katz
Robert Katz Publications
A particle which remains at rest or in uniform motion with respect to its frame of reference is said to be in equilibrium in that frame. Centuries ago it was recognized that the state of rest was a natural state of things, for it was observed that objects set in motion on the surface of the earth tended to come to rest. The maintenance of any horizontal motion on earth was thought to require the continued exercise of a force, hence to be a violent motion, while vertical motion like that of a falling body was thought to be natural …
Physics, Chatper 24: Potential, Henry Semat, Robert Katz
Physics, Chatper 24: Potential, Henry Semat, Robert Katz
Robert Katz Publications
A positive charge q situated at some point A in an electric field where the intensity is E will experience a force F given by Equation (23-1a) as F = Eq. In general, if this charge q is moved to some other point B in the electric field, an amount of work ΔW will have to be performed. The ratio of the work done ΔW to charge q transferred from point A to point B is called the difference of potential ΔV between these points.
Physics, Chapter 22: Electrostatics, Henry Semat, Robert Katz
Physics, Chapter 22: Electrostatics, Henry Semat, Robert Katz
Robert Katz Publications
One simple phenomenon of electricity was known to the ancients: that when a piece of amber was rubbed, it acquired the property of attracting small pieces of paper and other light particles. Records show that Thales of Miletus (circa sixth century B.C.) knew of this property of amber; the Greek word for amber is elektron, hence the name electricity. There was practically no further development of this subject until about the seventeenth century. Otto von Guericke (1602-1686) of Magdeburg built a large sulphur sphere, which, when rotated about an axis and rubbed with his hand, gave off electric sparks. In …
Physics, Chapter 25: Capacitance And Dielectrics, Henry Semat, Robert Katz
Physics, Chapter 25: Capacitance And Dielectrics, Henry Semat, Robert Katz
Robert Katz Publications
When an isolated charged conducting sphere bears a charge Q, the potential of the sphere may be computed from the results of Section 23-6 by considering that the electric intensity outside the sphere is as though the entire charge of the sphere were concentrated at its center.
Physics, Chapter 20: Wave Motion, Henry Semat, Robert Katz
Physics, Chapter 20: Wave Motion, Henry Semat, Robert Katz
Robert Katz Publications
Wave motion is an important method of transferring energy from one place to another without involving the actual transfer of matter. When a pebble is dropped into a still pool, some of the kinetic energy of the pebble is used to generate the ripples which spread out in all directions over the surface of the pool. When the ripples pass by a floating object, such as a bit of cork, the cork bobs up and down, having acquired its kinetic energy of vibration from the ripple system. The ripples thus serve to deliver some of the energy of the pebble …
Physics, Chapter 29: The Magnetic Field, Henry Semat, Robert Katz
Physics, Chapter 29: The Magnetic Field, Henry Semat, Robert Katz
Robert Katz Publications
Natural magnets, called lodestones, have been known since ancient times. The lodestone, a magnetic oxide of iron called magnetite (Fe3O4), was mentioned by Thales of Miletus. By the eleventh century the magnetic compass was known to the Chinese, and in the twelfth century references to the compass were made in Western Europe. The lodestone is capable of attracting pieces of iron and of imparting permanent magnetism to other pieces of iron so that these too could attract iron filings. If an iron bar is magnetized, as the result of being near a piece of lodestone, and …
Physics, Chapter 2: Motion Of A Particle (Kinematics), Henry Semat, Robert Katz
Physics, Chapter 2: Motion Of A Particle (Kinematics), Henry Semat, Robert Katz
Robert Katz Publications
Normally, when we say an object is at rest, we mean that it is at rest with respect to the surface of the earth; when we say a car is moving at a speed of 40 mi/hr, we imply that the motion is taking place at this speed relative to the road. A boat sailing on the river moves with respect to the river's banks, but it also moves with respect to the flowing water in the river. The lift on the wings of an airplane is generated by the motion of the airplane through the air, but it is …
Physics, Chapter 9: Hydrodynamics (Fluids In Motion), Henry Semat, Robert Katz
Physics, Chapter 9: Hydrodynamics (Fluids In Motion), Henry Semat, Robert Katz
Robert Katz Publications
When a liquid flows through a pipe in such a way that it completely fills the pipe, and as much liquid enters one end of the pipe as leaves the other end of the pipe in the same time, then the liquid is said to flow at a steady rate. At any point of the pipe, the flow of the liquid does not change with time. The path of any particle of liquid as it moves through the pipe is called a streamline. We can map the flow of liquid through the pipe by drawing a series of …
Physics, Chapter 4: Statics Of A Rigid Body, Henry Semat, Robert Katz
Physics, Chapter 4: Statics Of A Rigid Body, Henry Semat, Robert Katz
Robert Katz Publications
In the preceding chapter we observed that a particle would remain in equilibrium, in a state of rest, or in a state of uniform motion in a straight line when the resultant of all the forces acting on it was equal to zero. This condition for equilibrium was extended to larger bodies under either of two possible conditions: If the forces acting on the body were concurrent, that is, if they were directed toward a single point, the body could be treated as if it were a particle; or if the body moved with uniform translational motion in which every …
Physics, Chapter 17: The Phases Of Matter, Henry Semat, Robert Katz
Physics, Chapter 17: The Phases Of Matter, Henry Semat, Robert Katz
Robert Katz Publications
A substance which has a definite chemical composition can exist in one or more phases, such as the vapor phase, the liquid phase, or the solid phase. When two or more such phases are in equilibrium at any given temperature and pressure, there are always surfaces of separation between the two phases.
In the solid phase a pure substance generally exhibits a well-defined crystal structure in which the atoms or molecules of the substance are arranged in a repetitive lattice. Many substances are known to exist in several different solid phases at different conditions of temperature and pressure. These …
Physics, Chapter 45: Natural Radioactivity, Henry Semat, Robert Katz
Physics, Chapter 45: Natural Radioactivity, Henry Semat, Robert Katz
Robert Katz Publications
The discovery of an important phenomenon usually leads to other important discoveries. The discovery of x-rays by Roentgen in 1895 led to the discovery of radioactivity by Becquerel in 1896. In the gas type of x-ray tube used by Roentgen, the glass walls of the tube were observed to fluoresce. Becquerel was interested in determining whether there was any relationship between the fluorescence of the glass of an x-ray tube and the phosphorescence of certain salts which were irradiated by ordinary light. One of the salts used by Becquerel was the double sulphate of uranium and potassium. He wrapped a …
Physics, Chapter 44: Stable Nuclei, Henry Semat, Robert Katz
Physics, Chapter 44: Stable Nuclei, Henry Semat, Robert Katz
Robert Katz Publications
Atomic and nuclear physics are essentially twentieth-century developments, although these had their origins at the close of the nineteenth century. These developments followed two parallel streams, as shown in Figure 44-1, one dealing with the electronic structure of the atom and the other dealing with its nuclear structure. These two streams served to feed each other and were fed by all other branches of physics, but only a few of the more important contributions concerning the nature of radiation, matter, and energy are shown in the figure.
Physics, Chapter 42: Optical Spectra And Atomic Structure, Henry Semat, Robert Katz
Physics, Chapter 42: Optical Spectra And Atomic Structure, Henry Semat, Robert Katz
Robert Katz Publications
When light passes through a prism spectroscope or a diffraction-grating spectroscope, an optical spectrum is obtained in which the intensity of the radiation may be analyzed as a function of wavelength. The spectrum may be observed visually in the limited wavelength region to which the eye is sensitive; it may be focused on a photographic plate or upon a thermocouple or thermopile. Our knowledge of the structure of atoms and molecules is largely dependent upon the analyses of optical spectra, for these spectra are characteristic of the emitting atoms or molecules. Even before the spectra of atoms were properly understood …
Physics, Chapter 27: Direct-Current Circuits, Henry Semat, Robert Katz
Physics, Chapter 27: Direct-Current Circuits, Henry Semat, Robert Katz
Robert Katz Publications
When a charged particle traverses a closed path in an electrostatic field in space, the total work done on the particle is zero. The electric field is conservative. Associated with each point in the field, there is a fixed value of the electrical potential.
In a simple circuit consisting of a chemical cell and a resistor, as shown in Figure 27-1, we have seen that the current flows through the resistor from the positive terminal of the cell to the negative terminal of the cell. The positive terminal is at the higher potential, so that the current flows from the …
Physics, Chapter 28: Electrical Conduction In Liquids And Solids, Henry Semat, Robert Katz
Physics, Chapter 28: Electrical Conduction In Liquids And Solids, Henry Semat, Robert Katz
Robert Katz Publications
We have seen that electrical conduction in solids is associated with the drift of free electrons in the solid, a process which will be examined in greater detail in Section 28-4. A similar mechanism may be used to account for the conduction of electricity in liquid metals. In other liquids electricity is conducted by the migration of positive and negative ions through the liquid.
Physics, Chapter 10: Momentum And Impulse, Henry Semat, Robert Katz
Physics, Chapter 10: Momentum And Impulse, Henry Semat, Robert Katz
Robert Katz Publications
An extremely important concept in the development of mechanics is that of momentum. The momentum of a body is defined as the product of its mass by its velocity. We shall use the symbol p to denote the momentum of a body. The momentum of a body is a vector quantity, for it is the product of mass, a scalar, by velocity, a vector. While momentum and kinetic energy are compounded of the same two ingredients, mass and velocity, they are quite different concepts, and one aspect of their difference may be seen in the fact that momentum is …
Physics, Chapter 12: Periodic Motion, Henry Semat, Robert Katz
Physics, Chapter 12: Periodic Motion, Henry Semat, Robert Katz
Robert Katz Publications
One of the more important problems in mechanics is the study of periodic motions, that is, motions which repeat themselves in regular intervals of time, called the period. An example of periodic motion which we hrNe already encountered is uniform circular motion, in which the velocity and acceleration of the body at a given angular position were always the same. If a particle was found at a given position at a time t, we could be sure that it would return to that position at time t + T later, where T was the period of the rotational motion. A …
Physics, Chapter 21: Vibrations And Sound, Henry Semat, Robert Katz
Physics, Chapter 21: Vibrations And Sound, Henry Semat, Robert Katz
Robert Katz Publications
There are two aspects of sound: one is the physical aspect which involves the physics of the production, propagation, reception, and detection of sound; the other, which is the sensation of sound as perceived by the individual, depends upon physiological and psychological effects. It is not desirable to separate the two aspects of sound completely, but the main emphasis in this book must necessarily be on the physical aspect. In this chapter we shall consider mostly musical sounds. A vocabulary has been developed to describe the sensation experienced when a musical sound is heard. Such terms as the pitch of …
Physics, Chapter 11: Rotational Motion (The Dynamics Of A Rigid Body), Henry Semat, Robert Katz
Physics, Chapter 11: Rotational Motion (The Dynamics Of A Rigid Body), Henry Semat, Robert Katz
Robert Katz Publications
The motion of the flywheel of an engine and of a pulley on its axle are examples of an important type of motion of a rigid body, that of the motion of rotation about a fixed axis. Consider the motion of a uniform disk rotating about a fixed axis passing through its center of gravity C perpendicular to the face of the disk, as shown in Figure 11-1. The motion of this disk may be described in terms of the motions of each of its individual particles, but a better way to describe the motion is in terms of …
Physics, Chapter 19: Heat Engines, Henry Semat, Robert Katz
Physics, Chapter 19: Heat Engines, Henry Semat, Robert Katz
Robert Katz Publications
In this chapter we shall consider the physical principles underlying the operations of heat engines because of the intrinsic importance of these principles and because of the part they have played in the development of fundamental physical ideas. Heat engines are designed and built to convert heat into work. In most cases the heat is obtained from the combustion of a common fuel such as coal, oil, gasoline, or natural gas. An important new source of heat that is just beginning to be used, and will be used more extensively in the future, is the mass which is converted into …
Physics, Appendix B, Henry Semat, Robert Katz