Sinopsis
Science and engineering are based on measurements and comparisons. Thus, we need rules about how things are measured and compared, and we need experiments to establish the units for those measurements and comparisons. One purpose of physics (and engineering) is to design and conduct those experiments. For example, physicists strive to develop clocks of extreme accuracy so that any time or time interval can be precisely determined and compared. You may wonder whether such accuracy is actually needed or worth the effort. Here is one example of the worth: Without clocks of extreme accuracy, the Global Positioning System (GPS) that is now vital to worldwide navigation would be useless.
We discover physics by learning how to measure the quantities involved in physics. Among these quantities are length, time, mass, temperature, pressure, and electric current.
We measure each physical quantity in its own units, by comparison with a standard. The unit is a unique name we assign to measures of that quantity—for example, meter (m) for the quantity length.The standard corresponds to exactly 1.0 unit of the quantity. As you will see, the standard for length, which corresponds to exactly 1.0 m, is the distance traveled by light in a vacuum during a certain fraction of a second.We can define a unit and its standard in any way we care to. However, the important thing is to do so in such a way that scientists around the world will agree that our definitions are both sensible and practical. Once we have set up a standard—say, for length—we must work out procedures by which any length whatever, be it the radius of a hydrogen atom, the wheelbase of a skateboard, or the distance to a star, can be expressed in terms of the standard. Rulers, which approximate our length standard, give us one such procedure for measuring length. However, many of our comparisons must be indirect. You cannot use a ruler, for example, to measure the radius of an atom or the distance to a star.
There are so many physical quantities that it is a problem to organize them. Fortunately, they are not all independent; for example, speed is the ratio of a length to a time. Thus, what we do is pick out—by international agreement— a small number of physical quantities, such as length and time, and assign standards to them alone.We then define all other physical quantities in terms of these base quantities and their standards (called base standards). Speed, for example, is defined in terms of the base quantities length and time and their base standards. Base standards must be both accessible and invariable. If we define the length standard as the distance between one’s nose and the index finger on an outstretched arm, we certainly have an accessible standard—but it will, of course, vary from person to person.The demand for precision in science and engineering pushes us to aim first for invariability.We then exert great effort to make duplicates of the base standards that are accessible to those who need them.
Content
1 Measurement
2 Motion Along a Straight Line
3 Vectors
4 Motion in Two and Three Dimensions
5 Force and Motion — I
6 Force and Motion — II
7 Kinetic Energy and Work
8 Potential Energy and Conservation of Energy
9 Center of Mass and Linear Momentum
10 Rotation
11 Rolling, Torque, and Angular Momentum
12 Equilibrium and Elasticity
13 Gravitation
14 Fluids
15 Oscillations
16 Waves — I
17 Waves — II
18 Temperature, Heat, and the First Law of Thermodynamics
19 The Kinetic Theory of Gases
20 Entropy and the Second Law of Thermodynamics
21 Electric Charge
22 Electric Fields
23 Gauss’ Law
24 Electric Potential
25 Capacitance
26 Current and Resistance
27 Circuits
28 Magnetic Fields
29 Magnetic Fields Due to Currents
30 Induction and Inductance
31 Electromagnetic Oscillations and Alternating Current
32 Maxwell’s Equations; Magnetism of Matter
33 Electromagnetic Waves
34 Images
35 Interference
36 Diffraction
37 Relativity
38 Photons and Matter Waves
39 More About Matter Waves
40 All About Atoms
41 Conduction of Electricity in Solids
42 Nuclear Physics
43 Energy from the Nucleus
44 Quarks, Leptons, and the Big Bang
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