• Drag Forces

    • <definition id="fs-id1871378"> <term>drag force</term> <meaning id="fs-id1362788"> <m:math><m:semantics><m:mrow><m:mrow><m:msub><m:mi>F</m:mi><m:mrow><m:mtext>D</m:mtext></m:mrow></m:msub></m:mrow><m:mrow/></m:mrow><m:annotation encoding="StarMath 5.0"> size 12{F rSub { size 8{D} } } {}</m:annotation></m:semantics></m:math>, found to be proportional to the square of the speed of the object; mathematically <equation id="fs-id2600233"> <m:math> <m:semantics> <m:mrow> <m:mrow> <m:mrow> <m:mrow> <m:msub> <m:mi>F</m:mi> <m:mrow> <m:mtext>D</m:mtext> </m:mrow> </m:msub> <m:mo stretchy="false">&#8733;</m:mo> <m:mi/> </m:mrow> <m:msup> <m:mi>v</m:mi> <m:mrow> <m:mtext>2</m:mtext> </m:mrow> </m:msup> </m:mrow> </m:mrow> <m:mrow/> </m:mrow> <m:annotation encoding="StarMath 5.0"> size 12{F rSub { size 8{D} } prop `v rSup { size 8{2} } } {}</m:annotation> </m:semantics> </m:math> </equation> <equation id="fs-id2594583"> <m:math><m:semantics><m:mrow><m:mrow><m:mrow><m:mrow><m:msub><m:mi>F</m:mi><m:mrow><m:mtext>D</m:mtext></m:mrow></m:msub><m:mo stretchy="false">=</m:mo><m:mfrac><m:mn>1</m:mn><m:mn>2</m:mn></m:mfrac></m:mrow><m:mi fontstyle="italic">C&#961;</m:mi> <m:mrow><m:msup><m:mi fontstyle="italic">Av</m:mi><m:mrow><m:mn>2</m:mn></m:mrow></m:msup></m:mrow><m:mo>,</m:mo></m:mrow></m:mrow><m:mrow/></m:mrow><m:annotation encoding="StarMath 5.0"> size 12{F rSub { size 8{D} } = { {1} over {2} } C&#961; ital "Av" rSup { size 8{2} } } {}</m:annotation></m:semantics></m:math></equation> where <m:math><m:semantics><m:mrow><m:mrow><m:mi>C</m:mi></m:mrow><m:mrow/></m:mrow><m:annotation encoding="StarMath 5.0"> size 12{C} {}</m:annotation></m:semantics></m:math> is the drag coefficient, <m:math><m:semantics><m:mrow><m:mrow><m:mi>A</m:mi></m:mrow><m:mrow/></m:mrow><m:annotation encoding="StarMath 5.0"> size 12{A} {}</m:annotation></m:semantics></m:math> is the area of the object facing the fluid, and <m:math><m:semantics><m:mrow><m:mrow><m:mi>&#961;</m:mi></m:mrow><m:mrow/></m:mrow><m:annotation encoding="StarMath 5.0"> size 12{&#961;} {}</m:annotation></m:semantics></m:math> is the density of the fluid</meaning></definition>
    • <definition id="import-auto-id1165298997412"><term>Stokes&#8217; law</term> <meaning id="fs-id1165298481238"><m:math><m:semantics><m:mrow><m:mrow><m:mrow><m:msub><m:mi>F</m:mi><m:mrow><m:mn>s</m:mn></m:mrow></m:msub><m:mo stretchy="false">=</m:mo><m:mn>6</m:mn><m:mi fontstyle="italic">&#960;r&#951;v</m:mi></m:mrow></m:mrow><m:mrow/></m:mrow><m:annotation encoding="StarMath 5.0"> size 12{F rSub { size 8{s} } =6&#960;r&#951;v} {}</m:annotation></m:semantics></m:math>, where <m:math> <m:semantics> <m:mi>r</m:mi> </m:semantics> </m:math> is the radius of the object, <m:math> <m:semantics> <m:mi>&#951;</m:mi> </m:semantics> </m:math> is the viscosity of the fluid, and <m:math> <m:semantics> <m:mi>v</m:mi> </m:semantics> </m:math> is the object&#8217;s velocity</meaning></definition>
  • Physical Quantities and Units

    • <definition id="import-auto-id3096670"><term>physical quantity </term><meaning id="fs-id3105089">a characteristic or property of an object that can be measured or calculated from other measurements</meaning></definition>
    • <definition id="import-auto-id3136233"><term>units </term><meaning id="fs-id3105099"> a standard used for expressing and comparing measurements</meaning></definition>
    • <definition id="import-auto-id2968885"><term>SI units </term><meaning id="fs-id1577059">the international system of units that scientists in most countries have agreed to use; includes units such as meters, liters, and grams</meaning></definition>
    • <definition id="import-auto-id2582101"><term>English units</term><meaning id="fs-id2018396"> system of measurement used in the United States; includes units of measurement such as feet, gallons, and pounds</meaning></definition>
    • <definition id="import-auto-id3401009"><term>fundamental units</term><meaning id="fs-id2991354"> units that can only be expressed relative to the procedure used to measure them</meaning></definition>
    • <definition id="import-auto-id2512053"><term>derived units</term><meaning id="fs-id3186991"> units that can be calculated using algebraic combinations of the fundamental units</meaning></definition>
    • <definition id="import-auto-id2771646"><term>second</term><meaning id="fs-id3187001"> the SI unit for time, abbreviated (s)</meaning></definition>
    • <definition id="import-auto-id2910820"><term>meter</term><meaning id="fs-id3201842"> the SI unit for length, abbreviated (m)</meaning></definition>
    • <definition id="import-auto-id2806926"><term>kilogram</term><meaning id="fs-id2573988"> the SI unit for mass, abbreviated (kg)</meaning></definition>
    • <definition id="import-auto-id1990374"><term>metric system</term><meaning id="fs-id2573998"> a system in which values can be calculated in factors of 10</meaning></definition>
    • <definition id="import-auto-id1950368"><term>order of magnitude</term><meaning id="fs-id3348791"> refers to the size of a quantity as it relates to a power of 10</meaning></definition>
    • <definition id="import-auto-id2656746"><term>conversion factor</term><meaning id="fs-id1434398"> a ratio expressing how many of one unit are equal to another unit</meaning></definition>
  • Friction

    • <definition id="import-auto-id1165298863624"><term>friction</term> <meaning id="fs-id1617065">a force that opposes relative motion or attempts at motion between systems in contact</meaning></definition>
    • <definition id="import-auto-id1165298540973"><term>kinetic friction</term> <meaning id="fs-id1334613"> a force that opposes the motion of two systems that are in contact and moving relative to one another</meaning></definition>
    • <definition id="fs-id1763916"><term>static friction</term> <meaning id="fs-id1350812"> a force that opposes the motion of two systems that are in contact and are not moving relative to one another</meaning></definition>
    • <definition id="import-auto-id1165298540975"><term>magnitude of static friction</term> <meaning id="fs-id1522740"><m:math><m:semantics><m:mrow><m:mrow><m:mrow><m:mrow><m:msub><m:mi>f</m:mi><m:mrow><m:mn>s</m:mn></m:mrow></m:msub><m:mo stretchy="false">&#8804;</m:mo><m:msub><m:mi>&#956;</m:mi><m:mrow><m:mn>s</m:mn></m:mrow></m:msub></m:mrow><m:mspace width="0.25em"/><m:mi>N</m:mi></m:mrow></m:mrow><m:mrow/></m:mrow><m:annotation encoding="StarMath 5.0"> size 12{f rSub { size 8{s} } &lt;= &#956; rSub { size 8{s} } N} {}</m:annotation></m:semantics></m:math>, where <m:math><m:semantics><m:mrow><m:mrow><m:msub><m:mi>&#956;</m:mi><m:mrow><m:mn>s</m:mn></m:mrow></m:msub></m:mrow><m:mrow/></m:mrow></m:semantics></m:math> is the coefficient of static friction and <m:math><m:semantics><m:mi>N</m:mi></m:semantics></m:math> is the magnitude of the normal force</meaning></definition>
    • <definition id="import-auto-id1165298541210"><term>magnitude of kinetic friction</term><meaning id="fs-id1791136"><m:math><m:semantics><m:mrow><m:mrow><m:mrow><m:mrow><m:msub><m:mi>f</m:mi><m:mrow><m:mn>k</m:mn></m:mrow></m:msub><m:mo stretchy="false">=</m:mo><m:msub><m:mi>&#956;</m:mi><m:mrow><m:mn>k</m:mn></m:mrow></m:msub></m:mrow><m:mi>N</m:mi></m:mrow></m:mrow><m:mrow/></m:mrow><m:annotation encoding="StarMath 5.0"> size 12{f rSub { size 8{k} } =&#956; rSub { size 8{k} } N} {}</m:annotation></m:semantics></m:math>, where <m:math><m:semantics><m:mrow><m:mrow><m:msub><m:mi>&#956;</m:mi><m:mrow><m:mn>k</m:mn></m:mrow></m:msub></m:mrow><m:mrow/></m:mrow><m:annotation encoding="StarMath 5.0"> size 12{&#956; rSub { size 8{K} } } {}</m:annotation></m:semantics></m:math> is the coefficient of kinetic friction</meaning></definition>
  • Accuracy, Precision, and Significant Figures

    • <definition id="import-auto-id2732619"><term>accuracy</term><meaning id="fs-id1590454"> the degree to which a measured value agrees with correct value for that measurement</meaning></definition>
    • <definition id="import-auto-id1292530"><term>method of adding percents</term><meaning id="fs-id2551172"> the percent uncertainty in a quantity calculated by multiplication or division is the sum of the percent uncertainties in the items used to make the calculation</meaning></definition>
    • <definition id="import-auto-id2502324"><term>percent uncertainty</term><meaning id="fs-id2732929"> the ratio of the uncertainty of a measurement to the measured value, expressed as a percentage</meaning></definition>
    • <definition id="import-auto-id1603950"><term>precision</term><meaning id="fs-id888171"> the degree to which repeated measurements agree with each other</meaning></definition>
    • <definition id="import-auto-id3041405"><term>significant figures</term><meaning id="fs-id1375519"> express the precision of a measuring tool used to measure a value</meaning></definition>
    • <definition id="import-auto-id1320014"><term>uncertainty</term><meaning id="fs-id1618593"> a quantitative measure of how much your measured values deviate from a standard or expected value</meaning></definition>
  • Physics: An Introduction

    • <definition id="import-auto-id1948935"><term>classical physics</term><meaning id="fs-id1535391"> physics that was developed from the Renaissance to the end of the 19th century</meaning></definition>
    • <definition id="import-auto-id1636862"><term>physics</term><meaning id="fs-id2631578"> the science concerned with describing the interactions of energy, matter, space, and time; it is especially interested in what fundamental mechanisms underlie every phenomenon</meaning></definition>
    • <definition id="import-auto-id1999008"><term>model</term><meaning id="fs-id2597883"> representation of something that is often too difficult (or impossible) to display directly</meaning></definition>
    • <definition id="import-auto-id3089935"><term>theory</term><meaning id="fs-id2914211"> an explanation for patterns in nature that is supported by scientific evidence and verified multiple times by various groups of researchers</meaning></definition>
    • <definition id="import-auto-id2724260"><term>law</term><meaning id="fs-id3039691"> a description, using concise language or a mathematical formula, a generalized pattern in nature that is supported by scientific evidence and repeated experiments</meaning></definition>
    • <definition id="import-auto-id2998505"><term>scientific method</term><meaning id="fs-id2656603"> a method that typically begins with an observation and question that the scientist will research; next, the scientist typically performs some research about the topic and then devises a hypothesis; then, the scientist will test the hypothesis by performing an experiment; finally, the scientist analyzes the results of the experiment and draws a conclusion</meaning></definition>
    • <definition id="import-auto-id2692942"><term>modern physics</term><meaning id="fs-id3147360"> the study of relativity, quantum mechanics, or both</meaning></definition>
    • <definition id="import-auto-id3113698"><term>relativity</term><meaning id="fs-id1954355"> the study of objects moving at speeds greater than about 1% of the speed of light, or of objects being affected by a strong gravitational field</meaning></definition>
    • <definition id="import-auto-id2723056"><term>quantum mechanics</term><meaning id="fs-id2573497"> the study of objects smaller than can be seen with a microscope</meaning></definition>
  • Elasticity: Stress and Strain

    • <definition id="import-auto-id1165298828407"><term>deformation</term> <meaning id="fs-id1165298696821">change in shape due to the application of force</meaning></definition>
    • <definition id="fs-id1987830"><term>Hooke&#8217;s law</term><meaning id="fs-id1987834">proportional relationship between the force <m:math><m:semantics><m:mrow><m:mrow><m:mi>F</m:mi></m:mrow><m:mrow/></m:mrow></m:semantics></m:math> on a material and the deformation <m:math><m:semantics><m:mrow><m:mrow><m:mn>&#916;</m:mn><m:mi fontstyle="italic">L</m:mi></m:mrow><m:mrow/></m:mrow></m:semantics></m:math> it causes, <m:math><m:semantics><m:mrow><m:mrow><m:mrow><m:mi>F</m:mi><m:mo stretchy="false">=</m:mo><m:mi fontstyle="italic">k</m:mi><m:mn>&#916;</m:mn><m:mi>L</m:mi></m:mrow></m:mrow><m:mrow/></m:mrow><m:annotation encoding="StarMath 5.0"> size 12{F=k&#916;L} {}</m:annotation></m:semantics></m:math></meaning> </definition>
    • <definition id="import-auto-id1165298828410"><term>tensile strength</term> <meaning id="fs-id1165298787406">measure of deformation for a given tension or compression</meaning></definition>
    • <definition id="import-auto-id1165298696762"><term>stress</term> <meaning id="fs-id1165298600243">ratio of force to area</meaning></definition>
    • <definition id="import-auto-id1165296377254"><term>strain</term> <meaning id="fs-id1165298840132">ratio of change in length to original length</meaning></definition>
    • <definition id="fs-id1268428"><term>shear deformation</term><meaning id="fs-id1268431">deformation perpendicular to the original length of an object</meaning></definition>
  • Approximation

    • <definition id="import-auto-id2912380"><term>approximation</term><meaning id="fs-id1363258"> an estimated value based on prior experience and reasoning</meaning></definition>