Physics I: Chapter 1

Reference: Beginning Physics I




Physics, Science, Mathematics, Absolute value, Variables, Function, Graph, Inverse function, Trigonometric Function, Simultaneous equations, Linear equation, Units, Standard, International System of Units (SI), Significant figures, Scientific notation



For details on the following concepts, please consult CHAPTER 1.

Origin: “pertaining to nature.” Physics is the science that deals with matter, energy, motion, and force.

Origin: “to know.” Science is systematic knowledge of the physical or material world gained through observation and experimentation.

Origin: “something learned.” Mathematics is the systematic treatment of magnitude, relationships between figures and forms, and relations between quantities expressed symbolically.

The value without regards to its sign.  It is the magnitude of a number.

Variables are quantities that can take on a range of values.

Origin: “performed, executed.” A function is a mathematical relationship between two variables. If one of the variables takes on a particular value, the relationship tells us the corresponding value of the other variable.

Whenever one has a mathematical relationship between two variables, one can represent the function by a two dimensional graph. Note: Look up the definitions of the following on page 3: axes, origin, independent variable, dependent variable, slope, intercept.

A function gives us a y value for every x value. Inverse function turns it around and gives us an x value for every y-value. To get the graph of inverse function, rotate the graph of the function 90 deg clockwise so that y appears along the horizontal.

Trigonometric Functions are most usually defined in terms of ratios of sides of a right triangle, in which the angle plays the role of the independent variable.

When we have two different relationships involving the same two variables, then both relationships can be valid only for specific values of the variables.

Such equation are represented by straight lines on a graph.

Origin: “unity.” Unit is an identity element. We need units of measurement to measure physical quantities, such as, length, area, volume, velocity, acceleration, mass, time and temperature. Not all measurable quantities require their own units. Often, the unit is automatically defined in terms of other units. Such units are called derived units. In the subject of mechanics, only three physical quantities must have their units defined independently. These three quantities are usually taken to be length, mass and time, and their units are called  fundamental units. It turns out that units can be treated algebraically in any physics equation.

The physical specimen, which defines the unit, is called the standard.

The set of units most commonly used throughout the world, and which is almost exclusively used in scientific work. In mechanics, the units are the meter, the kilogram, and the second, and are what is commonly called the mks system.

Whenever a measured value is given for a physical quantity, it can only be an approximation, because it is not possible to measure  anything with “infinite” accuracy. A scientist or engineer who specifies the numerical value of a physical quantity keeps only as many figures in the number as are justified by the accuracy to which the physical quantity is known. For any measured quantity there is always some uncertainty in the last digit given. The number of significant figures provide a rough measure of percent uncertainty.

Scientific notation is a method for expressing a given quantity as a number having significant digits necessary for a specified degree of accuracy, multiplied by 10 to the appropriate power, as 1385.62 written as 1.386 × 103.


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  • Anonymous  On November 18, 2022 at 2:55 AM

    I must take the Definitions of the terms only from the text or I can use other resourses like dictionaries,enciclopedia,ecc..I must define the terms before I read the text.Thanks.


  • vinaire  On November 18, 2022 at 5:44 AM

    These definitions together give you an overview of the chapter. This overview is just the starting point. If any disagreements (inconsistencies) come up at this point you must clarify them.

    You may definitely use other resources like dictionaries, encyclopedia, etc. The whole point is watching for inconsistencies and clarifying them for these key concepts. Inconsistencies are those things that do not make sense.

    Once you have clarified the basic inconsistencies in these key concepts, the study of the whole chapter will go much faster. More inconsistencies may come up during the study of the chapter, but they are going to be much easier to handle.


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