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SI units : the international system of units that scientists in most countries have agreed to use; includes units such as meters, liters, and grams | https://openstax.org/books/college-physics-2e/pages/1-glossary |
significant figures : express the precision of a measuring tool used to measure a value | https://openstax.org/books/college-physics-2e/pages/1-glossary |
theory : an explanation for patterns in nature that is supported by scientific evidence and verified multiple times by various groups of researchers | https://openstax.org/books/college-physics-2e/pages/1-glossary |
uncertainty : a quantitative measure of how much your measured values deviate from a standard or expected value | https://openstax.org/books/college-physics-2e/pages/1-glossary |
units : a standard used for expressing and comparing measurements | https://openstax.org/books/college-physics-2e/pages/1-glossary |
Science seeks to discover and describe the underlying order and simplicity in nature. | https://openstax.org/books/college-physics-2e/pages/1-section-summary |
Physics is the most basic of the sciences, concerning itself with energy, matter, space and time, and their interactions. | https://openstax.org/books/college-physics-2e/pages/1-section-summary |
Scientific laws and theories express the general truths of nature and the body of knowledge they encompass. These laws of nature are rules that all natural processes appear to follow. | https://openstax.org/books/college-physics-2e/pages/1-section-summary |
Physical quantities are a characteristic or property of an object that can be measured or calculated from other measurements. | https://openstax.org/books/college-physics-2e/pages/1-section-summary |
Units are standards for expressing and comparing the measurement of physical quantities. All units can be expressed as combinations of four fundamental units. | https://openstax.org/books/college-physics-2e/pages/1-section-summary |
The four fundamental units we will use in this text are the meter (for length), the kilogram (for mass), the second (for time), and the ampere (for electric current). These units are part of the metric system, which uses powers of 10 to relate quantities over the vast ranges encountered in nature. | https://openstax.org/books/college-physics-2e/pages/1-section-summary |
The four fundamental units are abbreviated as follows: meter, m; kilogram, kg; second, s; and ampere, A. The metric system also uses a standard set of prefixes to denote each order of magnitude greater than or lesser than the fundamental unit itself. | https://openstax.org/books/college-physics-2e/pages/1-section-summary |
Unit conversions involve changing a value expressed in one type of unit to another type of unit. This is done by using conversion factors, which are ratios relating equal quantities of different units. | https://openstax.org/books/college-physics-2e/pages/1-section-summary |
Accuracy of a measured value refers to how close a measurement is to the correct value. The uncertainty in a measurement is an estimate of the amount by which the measurement result may differ from this value. | https://openstax.org/books/college-physics-2e/pages/1-section-summary |
Precision of measured values refers to how close the agreement is between repeated measurements. | https://openstax.org/books/college-physics-2e/pages/1-section-summary |
The precision of ameasuring toolis related to the size of its measurement increments. The smaller the measurement increment, the more precise the tool. | https://openstax.org/books/college-physics-2e/pages/1-section-summary |
Significant figures express the precision of a measuring tool. | https://openstax.org/books/college-physics-2e/pages/1-section-summary |
When multiplying or dividing measured values, the final answer can contain only as many significant figures as the least precise value. | https://openstax.org/books/college-physics-2e/pages/1-section-summary |
When adding or subtracting measured values, the final answer cannot contain more decimal places than the least precise value. | https://openstax.org/books/college-physics-2e/pages/1-section-summary |
Scientists often approximate the values of quantities to perform calculations and analyze systems. | https://openstax.org/books/college-physics-2e/pages/1-section-summary |
acceleration : the rate of change in velocity; the change in velocity over time | https://openstax.org/books/college-physics-2e/pages/2-glossary |
acceleration due to gravity : acceleration of an object as a result of gravity | https://openstax.org/books/college-physics-2e/pages/2-glossary |
average acceleration : the change in velocity divided by the time over which it changes | https://openstax.org/books/college-physics-2e/pages/2-glossary |
average speed : distance traveled divided by time during which motion occurs | https://openstax.org/books/college-physics-2e/pages/2-glossary |
average velocity : displacement divided by time over which displacement occurs | https://openstax.org/books/college-physics-2e/pages/2-glossary |
deceleration : acceleration in the direction opposite to velocity; acceleration that results in a decrease in velocity | https://openstax.org/books/college-physics-2e/pages/2-glossary |
dependent variable : the variable that is being measured; usually plotted along theyy-axis | https://openstax.org/books/college-physics-2e/pages/2-glossary |
displacement : the change in position of an object | https://openstax.org/books/college-physics-2e/pages/2-glossary |
distance : the magnitude of displacement between two positions | https://openstax.org/books/college-physics-2e/pages/2-glossary |
distance traveled : the total length of the path traveled between two positions | https://openstax.org/books/college-physics-2e/pages/2-glossary |
elapsed time : the difference between the ending time and beginning time | https://openstax.org/books/college-physics-2e/pages/2-glossary |
free-fall : the state of movement that results from gravitational force only | https://openstax.org/books/college-physics-2e/pages/2-glossary |
independent variable : the variable that the dependent variable is measured with respect to; usually plotted along thexx-axis | https://openstax.org/books/college-physics-2e/pages/2-glossary |
instantaneous acceleration : acceleration at a specific point in time | https://openstax.org/books/college-physics-2e/pages/2-glossary |
instantaneous speed : magnitude of the instantaneous velocity | https://openstax.org/books/college-physics-2e/pages/2-glossary |
instantaneous velocity : velocity at a specific instant, or the average velocity over an infinitesimal time interval | https://openstax.org/books/college-physics-2e/pages/2-glossary |
kinematics : the study of motion without considering its causes | https://openstax.org/books/college-physics-2e/pages/2-glossary |
model : simplified description that contains only those elements necessary to describe the physics of a physical situation | https://openstax.org/books/college-physics-2e/pages/2-glossary |
position : the location of an object at a particular time | https://openstax.org/books/college-physics-2e/pages/2-glossary |
scalar : a quantity that is described by magnitude, but not direction | https://openstax.org/books/college-physics-2e/pages/2-glossary |
slope : the difference inyy-value (the rise) divided by the difference inxx-value (the run) of two points on a straight line | https://openstax.org/books/college-physics-2e/pages/2-glossary |
time : change, or the interval over which change occurs | https://openstax.org/books/college-physics-2e/pages/2-glossary |
vector : a quantity that is described by both magnitude and direction | https://openstax.org/books/college-physics-2e/pages/2-glossary |
y-intercept : they-y-value whenxx= 0, or when the graph crosses theyy-axis | https://openstax.org/books/college-physics-2e/pages/2-glossary |
Kinematics is the study of motion without considering its causes. In this chapter, it is limited to motion along a straight line, called one-dimensional motion. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
Displacement is the change in position of an object. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
In symbols, displacementÎxÎxis defined to beÎx=xfâx0,Îx=xfâx0,wherex0x0is the initial position andxfxfis the final position. In this text, the Greek letterÎÎ(delta) always means âchange inâ whatever quantity follows it. The SI unit for displacement is the meter (m). Displacement has a direction as well as... | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
When you start a problem, assign which direction will be positive. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
Distance is the magnitude of displacement between two positions. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
Distance traveled is the total length of the path traveled between two positions. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
A vector is any quantity that has magnitude and direction. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
A scalar is any quantity that has magnitude but no direction. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
Displacement and velocity are vectors, whereas distance and speed are scalars. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
In one-dimensional motion, direction is specified by a plus or minus sign to signify left or right, up or down, and the like. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
Time is measured in terms of change, and its SI unit is the second (s). Elapsed time for an event isÎt=tfât0,Ît=tfât0,wheretftfis the final time andt0t0is the initial time. The initial time is often taken to be zero, as if measured with a stopwatch; the elapsed time is then justtt. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
Average velocityv-v-is defined as displacement divided by the travel time. In symbols, average velocity isv-=ÎxÎt=xfâx0tfât0.v-=ÎxÎt=xfâx0tfât0. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
The SI unit for velocity is m/s. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
Velocity is a vector and thus has a direction. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
Instantaneous velocityvvis the velocity at a specific instant or the average velocity for an infinitesimal interval. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
Instantaneous speed is the magnitude of the instantaneous velocity. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
Instantaneous speed is a scalar quantity, as it has no direction specified. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
Average speed is the total distance traveled divided by the elapsed time. (Average speed isnotthe magnitude of the average velocity.) Speed is a scalar quantity; it has no direction associated with it. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
Acceleration is the rate at which velocity changes. In symbols,average accelerationa-a-isa-=ÎvÎt=vfâv0tfât0.a-=ÎvÎt=vfâv0tfât0. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
The SI unit for acceleration ism/s2m/s2. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
Acceleration is a vector, and thus has a both a magnitude and direction. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
Acceleration can be caused by either a change in the magnitude or the direction of the velocity. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
Instantaneous accelerationaais the acceleration at a specific instant in time. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
Deceleration is an acceleration with a direction opposite to that of the velocity. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
To simplify calculations we take acceleration to be constant, so thata-=aa-=aat all times. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
We also take initial time to be zero. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
Initial position and velocity are given a subscript 0; final values have no subscript. Thus,Ît=tÎx=xâx0Îv=vâv0Ît=tÎx=xâx0Îv=vâv0 | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
The following kinematic equations for motion with constantaaare useful:x=x0+v-tx=x0+v-tv-=v0+v2v-=v0+v2v=v0+atv=v0+atx=x0+v0t+12at2x=x0+v0t+12at2v2=v02+2axâx0v2=v02+2axâx0 | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
In vertical motion,yyis substituted forxx. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
The six basic problem solving steps for physics are:Step 1. Examine the situation to determine which physical principles are involved.Step 2. Make a list of what is given or can be inferred from the problem as stated (identify the knowns).Step 3. Identify exactly what needs to be determined in the problem (identify the... | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
Step 1. Examine the situation to determine which physical principles are involved. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
Step 2. Make a list of what is given or can be inferred from the problem as stated (identify the knowns). | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
Step 3. Identify exactly what needs to be determined in the problem (identify the unknowns). | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
Step 4. Find an equation or set of equations that can help you solve the problem. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
Step 5. Substitute the knowns along with their units into the appropriate equation, and obtain numerical solutions complete with units. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
Step 6. Check the answer to see if it is reasonable: Does it make sense? | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
An object in free-fall experiences constant acceleration if air resistance is negligible. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
On Earth, all free-falling objects have an acceleration due to gravitygg, which averagesg=9.80 m/s2.g=9.80 m/s2. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
Whether the accelerationashould be taken as+g+gorâgâgis determined by your choice of coordinate system. If you choose the upward direction as positive,a=âg=â9.80 m/s2a=âg=â9.80 m/s2is negative. In the opposite case,a=+g=9.80 m/s2a=+g=9.80 m/s2is positive. Since acceleration is constant, the kinematic equati... | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
For objects in free-fall, up is normally taken as positive for displacement, velocity, and acceleration. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
Graphs of motion can be used to analyze motion. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
Graphical solutions yield identical solutions to mathematical methods for deriving motion equations. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
The slope of a graph of displacementxxvs. timettis velocityvv. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
The slope of a graph of velocityvvvs. timettgraph is accelerationaa. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
Average velocity, instantaneous velocity, and acceleration can all be obtained by analyzing graphs. | https://openstax.org/books/college-physics-2e/pages/2-section-summary |
air resistance : a frictional force that slows the motion of objects as they travel through the air; when solving basic physics problems, air resistance is assumed to be zero | https://openstax.org/books/college-physics-2e/pages/3-glossary |
analytical method : the method of determining the magnitude and direction of a resultant vector using the Pythagorean theorem and trigonometric identities | https://openstax.org/books/college-physics-2e/pages/3-glossary |
classical relativity : the study of relative velocities in situations where speeds are less than about 1% of the speed of lightâthat is, less than 3000 km/s | https://openstax.org/books/college-physics-2e/pages/3-glossary |
commutative : refers to the interchangeability of order in a function; vector addition is commutative because the order in which vectors are added together does not affect the final sum | https://openstax.org/books/college-physics-2e/pages/3-glossary |
component (of a 2-d vector) : a piece of a vector that points in either the vertical or the horizontal direction; every 2-d vector can be expressed as a sum of two vertical and horizontal vector components | https://openstax.org/books/college-physics-2e/pages/3-glossary |
direction (of a vector) : the orientation of a vector in space | https://openstax.org/books/college-physics-2e/pages/3-glossary |
head (of a vector) : the end point of a vector; the location of the tip of the vectorâs arrowhead; also referred to as the âtipâ | https://openstax.org/books/college-physics-2e/pages/3-glossary |
head-to-tail method : a method of adding vectors in which the tail of each vector is placed at the head of the previous vector | https://openstax.org/books/college-physics-2e/pages/3-glossary |
kinematics : the study of motion without regard to mass or force | https://openstax.org/books/college-physics-2e/pages/3-glossary |
magnitude (of a vector) : the length or size of a vector; magnitude is a scalar quantity | https://openstax.org/books/college-physics-2e/pages/3-glossary |
motion : displacement of an object as a function of time | https://openstax.org/books/college-physics-2e/pages/3-glossary |
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