AP Physics 1 Unit 2: Force and Translational Dynamics PDF

AP PHYSICS 1 UNIT 2 Force and Translational Dynamics...

AP PHYSICS 1 UNIT 2 Force and Translational Dynamics 18–23% AP EXAM WEIGHTING ~22–27 CLASS PERIODS AP Physics 1: Algebra-Based Course and Exam Description Course Framework V.1 | 39 Return to Table of Contents © 2024 College Board  Remember to go to AP Classroom to assign students the online Progress Check for this unit. Whether assigned as homework or completed in class, the Progress Check provides each student with immediate feedback related to this unit’s topics and science practices. Progress Check 2 Multiple-choice: ~30 questions Free-response: 4 questions § Mathematical Routines § Translation Between Representations § Experimental Design and Analysis § Qualitative/Quantitative Translation AP Physics 1: Algebra-Based Course and Exam Description Course Framework V.1 | 40 Return to Table of Contents © 2024 College Board  UNIT 2 18–23% AP EXAM WEIGHTING ~22–27 CLASS PERIODS Force and Translational Dynamics Developing Understanding ESSENTIAL In Unit 2, students are introduced to the concept of force, which is an interaction between QUESTIONS two objects or systems of objects. Part of the larger study of dynamics, forces provide § Why do we feel pulled thecontextinwhichstudentsanalyzeandcometounderstandavarietyofphysical toward Earth but not phenomena. This understanding is accomplished by revisiting and building upon the models toward a pencil? andrepresentationspresentedinUnit1—specificallythroughtheintroductionofthefree- §§ Whyisitmoredifficult bodydiagram.Studentswillfurtheranalyzetheeffectofforcesonsystemswhenthey to stop a fully loaded encounter Newton’s second law in rotational form in Unit 5. dump truck than a small in the domain. This skill appears in the fourth passenger car? Building the Science questionofthefree-responsesection, §§ Whyisitdifficulttowalk Practices the Qualitative/Quantitative Translation on ice? 2.A 2.D 3.B 3.C (QQT) question. In this question, students §§ Why will a delivery truck Translation between models and demonstrate translation between words and filledwithbirdssitting representations is key in this unit. Students will mathematicsbydescribingandanalyzing onitsfloorbethesame continue to use models and representations a scenario. Using content from any unit, weight as a truck with the thatwillhelpthemfurtheranalyzesystems, theQQTfirstrequiresstudentstomakea samebirdsflyingaround the interactions between systems, and how claim and provide evidence and reasoning inside? these interactions result in change. Alongside to support their claim without reference gainingproficiencyintheuseofspecificforce to equations. Students are then asked to equations, Unit 2 also encourages students derive an equation or set of equations to to derive new expressions from fundamental mathematically represent the scenario. principles (2.A) to help them make Lastly, students are required to make a predictions using functional dependence connection between the claim made in the between variables (2.D). The skills of making firstpartofthequestionandtheequation(s) claims (3.B) and supporting those claims derived in the second part. Students using evidence (3.C) can be developed exposed primarily to numerical problem throughout the unit by providing students solving often struggle with the QQT because with opportunities such as having them it requires them to express a conceptual make predictions about the acceleration of a understanding of course content and system based on the forces exerted on that representations. Opportunities to translate system, and then justifying those predictions betweendifferentrepresentations,including with appropriate physics principles. equations, diagrams, graphs, and verbal descriptions, can help students prepare for Preparing for the AP Exam the QQT question. The AP Physics 1 Exam requires students tore-expresskeyelementsofphysical phenomena across multiple representations AP Physics 1: Algebra-Based Course and Exam Description Course Framework V.1 | 41 Return to Table of Contents © 2024 College Board  UNIT 2 Force and Translational Dynamics UNIT AT A GLANCE Topic Suggested Skills 2.1 Systems and Center 1.B Create quantitative graphs with appropriate scales and units, including plotting data. of Mass 2.B Calculate or estimate an unknown quantity with units from known quantities, by selecting and following a logical computational pathway. 2.C Comparephysicalquantitiesbetweentwoormorescenariosoratdifferenttimesand locations in a single scenario. 3.B 2.2 Forces and 1.A Create diagrams, tables, charts, or schematics to represent physical situations. Free-Body Diagrams 2.B Calculate or estimate an unknown quantity with units from known quantities, by selecting and following a logical computational pathway. 2.C 3.C Justify or support a claim using evidence from experimental data, physical representations, or physical principles or laws. 2.3 Newton’s Third Law 1.A Create diagrams, tables, charts, or schematics to represent physical situations. 2.D Predict new values or factors of change of physical quantities using functional dependence between variables. 3.B Applyanappropriatelaw,definition,theoreticalrelationship,ormodeltomakeaclaim. 3.C Justify or support a claim using evidence from experimental data, physical representations, or physical principles or laws. 2.4 Newton’s First Law 1.C Create qualitative sketches of graphs that represent features of a model or the behavior of a physicalsystem. 2.A Derive a symbolic expression from known quantities by selecting and following a logical mathematical pathway. 3.B 3.C Justify or support a claim using evidence from experimental data, physical representations, or physical principles or laws. continued on next page AP Physics 1: Algebra-Based Course and Exam Description Course Framework V.1 | 42 Return to Table of Contents © 2024 College Board  UNIT Force and Translational Dynamics 2 UNIT AT A GLANCE (cont’d) Topic Suggested Skills 2.5 Newton’s Second 1.A Create diagrams, tables, charts, or schematics to represent physical situations. Law 2.A Derive a symbolic expression from known quantities by selecting and following a logical mathematical pathway. 2.D Predict new values or factors of change of physical quantities using functional dependence between variables. 3.B Applyanappropriatelaw,definition,theoreticalrelationship,ormodeltomakeaclaim. 2.6 Gravitational Force 1.A Create diagrams, tables, charts, or schematics to represent physical situations. 2.A Derive a symbolic expression from known quantities by selecting and following a logical mathematical pathway. 2.D Predict new values or factors of change of physical quantities using functional dependence between variables. 3.C Justify or support a claim using evidence from experimental data, physical representations, or physical principles or laws. 2.7 Kinetic and Static 1.C Create qualitative sketches of graphs that represent features of a model or the behavior of a Friction physical system. 2.B Calculate or estimate an unknown quantity with units from known quantities, by selecting and following a logical computational pathway. 2.C Comparephysicalquantitiesbetweentwoormorescenariosoratdifferenttimesand locations in a single scenario. 3.B Applyanappropriatelaw,definition,theoreticalrelationship,ormodeltomakeaclaim. continued on next page AP Physics 1: Algebra-Based Course and Exam Description Course Framework V.1 | 43 Return to Table of Contents © 2024 College Board  UNIT 2 Force and Translational Dynamics UNIT AT A GLANCE (cont’d) Topic Suggested Skills 2.8 Spring Forces 1.B Create quantitative graphs with appropriate scales and units, including plotting data. 2.A Derive a symbolic expression from known quantities by selecting and following a logical mathematical pathway. 2.C Comparephysicalquantitiesbetweentwoormorescenariosoratdifferenttimesand locations in a single scenario. 3.A Createexperimentalproceduresthatareappropriateforagivenscientificquestion. 3.B Applyanappropriatelaw,definition,theoreticalrelationship,ormodeltomakeaclaim. 2.9 Circular Motion 1.B Create quantitative graphs with appropriate scales and units, including plotting data. 2.A Derive a symbolic expression from known quantities by selecting and following a logical mathematical pathway. 2.D Predict new values or factors of change of physical quantities using functional dependence between variables. 3.A Createexperimentalproceduresthatareappropriateforagivenscientificquestion. 3.C Justify or support a claim using evidence from experimental data, physical representations, or physical principles or laws. Go to AP Classroom to assign the Progress Check for Unit 2. Review the results in class to identify and address any student misunderstandings. AP Physics 1: Algebra-Based Course and Exam Description Course Framework V.1 | 44 Return to Table of Contents © 2024 College Board  UNIT Force and Translational Dynamics 2 SAMPLE INSTRUCTIONAL ACTIVITIES Thesampleactivitiesonthispageareoptionalandareofferedtoprovidepossiblewaysto incorporate various instructional approaches in the classroom. Teachers do not need to use these activities or instructional approaches and are free to alter or edit them. The examples below were developed in partnership with teachers from the AP community to share ways that they approach teaching some of the topics in this unit. Please refer to the Instructional Approaches section beginning on p. 153 for more examples of activities and strategies. Activity Topic Sample Activity 1 2.2 Changing Representations Havestudentsconsideranacceleratingtwo-objectsystemfromeverydaylife(e.g.,person pushes a shopping cart, car pulls a trailer). Have them draw the forces on one object, then ontheother,andthentheexternalforcesexertedonthetwo-objectsystem. 2 2.5 Working Backward Put students in pairs. Have student A write a Newton’s second law equation either with symbolsorplugged-innumbersincludingunits.Then,havestudentBdescribeasituation that the equation applies to, including the object’s velocity direction and how velocity is changing,adiagram,andafree-bodydiagram. 3 2.5 What, If Anything, Is Wrong? Havestudentsidentifysomeforce-relatedproblemfromtheirhomeworkortextbook(that requires setting up Newton’s second law and maybe more). Ask students to write out a detailed solution that has exactly one mistake in it (not a calculation error). Post everyone’s problems/solutions, and then ask students to identify everyone else’s errors. The last student to have their error found wins. 4 2.7 Desktop Experiment Task Havestudentsmeasurethecoefficientofstaticfrictionoftheirshoeonawoodplankor metal track. Level 1: Use a spring scale. Level 2: Use a pulley, a spring, a toy bucket, and an electronic balance. Level 3: Use a protractor. 5 2.6/2.9 Desktop Experiment Task Have students use the “My Solar System” PhET applet to create circular orbits of varying radii around the central star and record radius, period, and planet mass for various trials. Next, have them calculate the speed using v = 2 r/T and force using F = mv 2 /r. Using the data, have students show that gravitational force is directly proportional to the mass of each object and inversely proportional to the square of the radius. 6 2.9 Construct an Argument Askstudentstoconsidertwoidenticalobjectsmovingincircles(orpartsofcircles)ofdifferent radii. Then, ask them to think of a situation where the object with the smaller radius has a greater net force and another situation where the object with the larger radius has a greater net force. 7 2.9 Changing Representations Describe something a driver could be doing in a car (e.g., “turning the steering wheel to the right while pressing the brake”). Have students walk out the motion while holding out one arm representing the velocity vector and the other arm representing the acceleration vector. 8 2.9 Predict and Explain Attach an object of known weight (say, 2 N) to a force sensor and cause the object to swing ina180-degreearc.Askstudents,“Atthebottom,theobjectisneitherspeedingupnor slowing down, so what force is registered at the bottom?” Expect students to (incorrectly) answer, “2 N” and discuss, as a class, why this answer is incorrect. AP Physics 1: Algebra-Based Course and Exam Description Course Framework V.1 | 45 Return to Table of Contents © 2024 College Board  UNIT 2 Force and Translational Dynamics SUGGESTED SKILLS 1.B TOPIC 2.1 Systems and Create quantitative graphs with appropriate scales and units, including plotting Center of Mass data. 2.B Calculate or estimate an unknown quantity with units from known quantities, by selecting and following a logical computational pathway. 2.C Compare physical Required Course Content quantities between two or more scenarios or atdifferenttimesand locations in a single LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE scenario. 2.1.A 2.1.A.1 3.B Describe the properties and System properties are determined by the Apply an appropriate law, interactions of a system. interactions between objects within the definition,theoretical system. relationship, or model to make a claim. 2.1.A.2 If the properties or interactions of the constituent objects within a system are not important in modeling the behavior of the macroscopic system, the system can itself be treated as a single object. 2.1.A.3 Systems may allow interactions between constituent parts of the system and the environment, which may result in the transfer of energy or mass. 2.1.A.4 Individual objects within a chosen system may behavedifferentlyfromeachotheraswellas from the system as a whole. 2.1.A.5 Theinternalstructureofasystemaffectsthe analysis of that system. 2.1.A.6 As variables external to a system are changed, the system’s substructure may change. continued on next page AP Physics 1: Algebra-Based Course and Exam Description Course Framework V.1 | 46 Return to Table of Contents © 2024 College Board  UNIT Force and Translational Dynamics 2 LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE 2.1.B 2.1.B.1 Describe the location of a For systems with symmetrical mass system’s center of mass distributions, the center of mass is located on with respect to the system’s lines of symmetry. constituent parts. 2.1.B.2 The location of a system’s center of mass along a given axis can be calculated using the equation   x cm = ∑mi x i ∑mi 2.1.B.3 A system can be modeled as a singular object that is located at the system’s center of mass. BOUNDARY STATEMENT AP Physics 1 only expects students to calculate the center of mass for systems of five or fewer particles arranged in a two-dimensional configuration or for systems that are highly symmetrical. AP Physics 1: Algebra-Based Course and Exam Description Course Framework V.1 | 47 Return to Table of Contents © 2024 College Board  UNIT 2 Force and Translational Dynamics SUGGESTED SKILLS 1.A TOPIC 2.2 Forces and Create diagrams, tables, charts, or schematics to represent physical Free-Body Diagrams situations. 2.B Calculate or estimate an unknown quantity with units from known quantities, by selecting and following a logical computational pathway. 2.C Compare physical Required Course Content quantities between two or more scenarios or atdifferenttimesand locations in a single LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE scenario. 2.2.A 2.2.A.1 3.C Describe a force as an Forces are vector quantities that describe the Justify or support a claim interaction between two interactions between objects or systems. using evidence from objects or systems. experimental data, physical 2.2.A.1.i representations, or physical A force exerted on an object or system is principles or laws. always due to the interaction of that object with another object or system. 2.2.A.1.ii An object or system cannot exert a net force on itself. 2.2.A.2 Contact forces describe the interaction of an object or system touching another object orsystemandaremacroscopiceffectsof interatomic electric forces. 2.2.B 2.2.B.1 Describe the forces exerted Free-bodydiagramsareusefultoolsfor on an object or system using visualizingforcesbeingexertedonasingle afree-bodydiagram. object or system and for determining the equations that represent a physical situation. 2.2.B.2 Thefree-bodydiagramofanobjectorsystem shows each of the forces exerted on the object by the environment. 2.2.B.3 Forces exerted on an object or system are represented as vectors originating from the representation of the center of mass, such as a dot. A system is treated as though all of its mass is located at the center of mass. continued on next page AP Physics 1: Algebra-Based Course and Exam Description Course Framework V.1 | 48 Return to Table of Contents © 2024 College Board  UNIT Force and Translational Dynamics 2 LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE 2.2.B 2.2.B.4 Describe the forces exerted A coordinate system with one axis parallel to on an object using a free- the direction of acceleration of the object or body diagram. systemsimplifiesthetranslationfromfree- body diagram to algebraic representation. For example,inafree-bodydiagramofanobject on an inclined plane, it is useful to set one axis parallel to the surface of the incline. BOUNDARY STATEMENT AP Physics 1 only expects students to depict the forces exerted on objects, not the force components on free-body diagrams. On the AP Physics exams, individual forces represented on a free-body diagram must be drawn as individual straight arrows, originating on the dot and pointing in the direction of the force. Individual forces that are in the same direction must be drawn side by side, not overlapping. AP Physics 1: Algebra-Based Course and Exam Description Course Framework V.1 | 49 Return to Table of Contents © 2024 College Board  UNIT 2 Force and Translational Dynamics SUGGESTED SKILLS 1.A TOPIC 2.3 Newton’s Third Law Create diagrams, tables, charts, or schematics to represent physical situations. 2.D Predict new values or factors of change of physical quantities using functional dependence between variables. 3.B Apply an appropriate law, definition,theoretical Required Course Content relationship, or model to make a claim. 3.C Justify or support a claim LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE using evidence from 2.3.A 2.3.A.1 experimental data, physical Describe the interaction of Newton’s third law describes the interaction of representations, or physical two objects using Newton’s two objects in terms of the paired forces that principles or laws. third law and a representation each exerts on the other. of paired forces exerted on each object. 2.3.A.2 Interactions between objects within a system (internalforces)donotinfluencethemotionof a system’s center of mass. 2.3.A.3 Tension is the macroscopic net result of forces that segments of a string, cable, chain, or similar system exert on each other in response to an external force. 2.3.A.3.i An ideal string has negligible mass and does not stretch when under tension. 2.3.A.3.ii The tension in an ideal string is the same at all points within the string. 2.3.A.3.iii In a string with nonnegligible mass, tension may not be the same at all points within the string. 2.3.A.3.iv An ideal pulley is a pulley that has negligible mass and rotates about an axle through its center of mass with negligible friction. continued on next page AP Physics 1: Algebra-Based Course and Exam Description Course Framework V.1 | 50 Return to Table of Contents © 2024 College Board  UNIT Force and Translational Dynamics 2 LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE 2.3.A Describe the interaction of two objects using Newton’s third law and a representation of paired forces exerted on each object. BOUNDARY STATEMENT AP Physics 1 only expects students to describe tension qualitatively in a string, cable, chain, or similar system with mass. For example, students might note that the tension in a hanging chain is greater toward the top of the chain. BOUNDARY STATEMENT The interaction between objects or systems at a distance is limited to gravitational forces in AP Physics 1. In AP Physics 2, gravitational, electric, and magnetic forces may be considered. AP Physics 1: Algebra-Based Course and Exam Description Course Framework V.1 | 51 Return to Table of Contents © 2024 College Board  UNIT 2 Force and Translational Dynamics SUGGESTED SKILLS 1.C TOPIC 2.4 Newton’s First Law Create qualitative sketches of graphs that represent features of a model or the behavior of a physical system. 2.A Derive a symbolic expression from known quantities by selecting and following a logical mathematical pathway. 3.B Apply an appropriate law, Required Course Content definition,theoretical relationship, or model to make a claim. 3.C LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE Justify or support a claim 2.4.A 2.4.A.1 using evidence from Describe the conditions The net force on a system is the vector sum of experimental data, physical under which a system’s all forces exerted on the system. representations, or physical velocity remains constant. principles or laws. 2.4.A.2 Translationalequilibriumisaconfigurationof forces such that the net force exerted on a systemiszero. Derived equation: i 2.4.A.3 Newton’sfirstlawstatesthatifthenetforce exertedonasystemiszero,thevelocityofthat system will remain constant. 2.4.A.4 Forces may be balanced in one dimension but unbalanced in another. The system’s velocity will change only in the direction of the unbalanced force. 2.4.A.5 An inertial reference frame is one from which anobserverwouldverifyNewton’sfirstlawof motion. AP Physics 1: Algebra-Based Course and Exam Description Course Framework V.1 | 52 Return to Table of Contents © 2024 College Board  UNIT Force and Translational Dynamics 2 TOPIC 2.5 SUGGESTED SKILLS 1.A Newton’s Second Law Create diagrams, tables, charts, or schematics to represent physical situations. 2.A Derive a symbolic expression from known quantities by selecting and following a logical mathematical pathway. 2.D Required Course Content Predict new values or factors of change of physical quantities using functional dependence between variables. LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE 3.B 2.5.A 2.5.A.1 Apply an appropriate law, Describe the conditions Unbalancedforcesareaconfigurationof definition,theoretical relationship, or model to under which a system’s forces such that the net force exerted on a make a claim. velocity changes. systemisnotequaltozero. 2.5.A.2 Newton’s second law of motion states that the acceleration of a system’s center of mass has a magnitude proportional to the magnitude of the net force exerted on the system and is in the same direction as that net force. Relevant equation: 2.5.A.3 The velocity of a system’s center of mass will onlychangeifanonzeronetexternalforceis exerted on that system. AP Physics 1: Algebra-Based Course and Exam Description Course Framework V.1 | 53 Return to Table of Contents © 2024 College Board  UNIT 2 Force and Translational Dynamics SUGGESTED SKILLS 1.A TOPIC 2.6 Gravitational Force Create diagrams, tables, charts, or schematics to represent physical situations. 2.A Derive a symbolic expression from known quantities by selecting and following a logical mathematical pathway. 2.D Predict new values or factors of change of Required Course Content physical quantities using functional dependence between variables. 3.C LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE Justify or support a claim 2.6.A 2.6.A.1 using evidence from Describe the gravitational Newton’s law of universal gravitation describes experimental data, physical interaction between two the gravitational force between two objects representations, or physical objects or systems with or systems as directly proportional to each of principles or laws. mass. their masses and inversely proportional to the square of the distance between the systems’ centers of mass. Relevant equation: 2.6.A.1.i The gravitational force is attractive. 2.6.A.1.ii The gravitational force is always exerted along the line connecting the centers of mass of the two interacting systems. 2.6.A.1.iii The gravitational force on a system can be considered to be exerted on the system’s center of mass. 2.6.A.2 Afieldmodelstheeffectsofanoncontact force exerted on an object at various positions in space. 2.6.A.2.i The magnitude of the gravitational field created by a system of mass M at a point in space is equal to the ratio of the gravitational force exerted by the system on a test object of mass m to the mass of the test object. continued on next page AP Physics 1: Algebra-Based Course and Exam Description Course Framework V.1 | 54 Return to Table of Contents © 2024 College Board  UNIT Force and Translational Dynamics 2 LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE 2.6.A Derived equation: Describe the gravitational interaction between two objects with mass. 2.6.A.2.ii If the gravitational force is the only force exerted on an object, the observed acceleration of the object (in m/s2) is numerically equal to the magnitude of the gravitationalfieldstrength(inN/kg)atthat location. 2.6.A.3 The gravitational force exerted by an astronomical body on a relatively small nearby object is called weight. Derived Equation: Weight = Fg = mg 2.6.B 2.6.B.1 Describe situations in which If the gravitational force between two systems’ the gravitational force can be centers of mass has a negligible change as the considered constant. relative position of the two systems changes, the gravitational force can be considered constant at all points between the initial and finalpositionsofthesystems. 2.6.B.2 Near the surface of Earth, the strength of the gravitationalfieldis g ≈ 10 N/kg 2.6.C 2.6.C.1 Describe the conditions The magnitude of the apparent weight of a under which the magnitude of system is the magnitude of the normal force a system’s apparent weight is exerted on the system. differentfromthemagnitude 2.6.C.2 of the gravitational force If the system is accelerating, the apparent weight exerted on that system. of the system is not equal to the magnitude of the gravitational force exerted on the system. 2.6.C.3 A system appears weightless when there are no forces exerted on the system or when the force of gravity is the only force exerted on the system. 2.6.C.4 The equivalence principle states that an observer in a noninertial reference frame is unable to distinguish between an object’s apparent weight and the gravitational force exertedontheobjectbyagravitationalfield. continued on next page AP Physics 1: Algebra-Based Course and Exam Description Course Framework V.1 | 55 Return to Table of Contents © 2024 College Board  UNIT 2 Force and Translational Dynamics LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE 2.6.D 2.6.D.1 Describe inertial and Objects have inertial mass, or inertia, a gravitational mass. property that determines how much an object’s motion resists changes when interacting with another object. 2.6.D.2 Gravitational mass is related to the force of attraction between two systems with mass. 2.6.D.3 Inertial mass and gravitational mass have been experimentallyverifiedtobeequivalent. AP Physics 1: Algebra-Based Course and Exam Description Course Framework V.1 | 56 Return to Table of Contents © 2024 College Board  UNIT Force and Translational Dynamics 2 TOPIC 2.7 SUGGESTED SKILLS 1.C Kinetic and Create qualitative sketches of graphs that represent features of a model or Static Friction the behavior of a physical system. 2.B Calculate or estimate an unknown quantity with units from known quantities, by selecting and following a logical computational pathway. Required Course Content 2.C Compare physical quantities between two or more scenarios or LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE atdifferenttimesand locations in a single 2.7.A 2.7.A.1 scenario. Describe kinetic friction Kinetic friction occurs when two surfaces in 3.B between two surfaces contact move relative to each other. Apply an appropriate law, 2.7.A.1.i definition,theoretical The kinetic friction force is exerted in a relationship, or model to direction opposite to the motion of each make a claim. surface relative to the other surface. 2.7.A.1.ii The force of friction between two surfaces doesnotdependonthesizeofthesurface area of contact. 2.7.A.2 The magnitude of the kinetic friction force exerted on an object is the product of the normal force the surface exerts on the object andthecoefficientofkineticfriction. Relevant equation: 2.7.A.2.i Thecoefficientofkineticfrictiondepends on the material properties of the surfaces that are in contact. 2.7.A.2.ii Normal force is the perpendicular component of the force exerted on an object by the surface with which it is in contact; it is directed away from the surface. continued on next page AP Physics 1: Algebra-Based Course and Exam Description Course Framework V.1 | 57 Return to Table of Contents © 2024 College Board  UNIT 2 Force and Translational Dynamics LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE 2.7.B 2.7.B.1 Describe static friction Static friction may occur between the between two surfaces. contacting surfaces of two objects that are not moving relative to each other. 2.7.B.2 Static friction adopts the value and direction required to prevent an object from slipping or sliding on a surface. Relevant equation: f ,s s n 2.7.B.2.i Slipping and sliding refer to situations in which two surfaces are moving relative to each other. 2.7.B.2.ii There exists a maximum value for which static friction will prevent an object from slipping on a given surface. Derived equation: F f ,s ,max = µ s Fn 2.7.B.3 Thecoefficientofstaticfrictionistypically greaterthanthecoefficientofkineticfriction for a given pair of surfaces. AP Physics 1: Algebra-Based Course and Exam Description Course Framework V.1 | 58 Return to Table of Contents © 2024 College Board  UNIT Force and Translational Dynamics 2 TOPIC 2.8 SUGGESTED SKILLS 1.B Spring Forces Create quantitative graphs with appropriate scales and units, including plotting data. 2.A Derive a symbolic expression from known quantities by selecting and following a logical mathematical pathway. 2.C Required Course Content Compare physical quantities between two or more scenarios or atdifferenttimesand locations in a single LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE scenario. 2.8.A 2.8.A.1 3.A Describe the force exerted on An ideal spring has negligible mass and exerts Create experimental procedures that are an object by an ideal spring a force that is proportional to the change in its appropriate for a given length as measured from its relaxed length. scientificquestion. 2.8.A.2 3.B The magnitude of the force exerted by an ideal Apply an appropriate law, spring on an object is given by Hooke’s law: definition,theoretical relationship, or model to make a claim. 2.8.A.3 The force exerted on an object by a spring is always directed toward the equilibrium position of the object–spring system. AP Physics 1: Algebra-Based Course and Exam Description Course Framework V.1 | 59 Return to Table of Contents © 2024 College Board  UNIT 2 Force and Translational Dynamics SUGGESTED SKILLS 1.B TOPIC 2.9 Circular Motion Create quantitative graphs with appropriate scales and units, including plotting data. 2.A Derive a symbolic expression from known quantities by selecting and following a logical mathematical pathway. 2.D Predict new values or factors of change of Required Course Content physical quantities using functional dependence between variables. 3.A LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE Create experimental 2.9.A 2.9.A.1 procedures that are Describe the motion of an Centripetal acceleration is the component of appropriate for a given object traveling in a circular an object’s acceleration directed toward the scientificquestion. path. center of the object’s circular path. 3.C 2.9.A.1.i Justify or support a claim using evidence from The magnitude of centripetal acceleration experimental data, physical for an object moving in a circular path is representations, or physical the ratio of the object’s tangential speed principles or laws. squared to the radius of the circular path. Relevant equation: 2.9.A.1.ii Centripetal acceleration is directed toward the center of an object’s circular path. 2.9.A.2 Centripetal acceleration can result from a single force, more than one force, or components of forces exerted on an object in circular motion. 2.9.A.2.i At the top of a vertical, circular loop, an object requires a minimum speed to maintain circular motion. At this point, and with this minimum speed, the gravitational force is the only force that causes the centripetal acceleration. Derived equation: continued on next page AP Physics 1: Algebra-Based Course and Exam Description Course Framework V.1 | 60 Return to Table of Contents © 2024 College Board  UNIT Force and Translational Dynamics 2 LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE 2.9.A 2.9.A.2.ii Describe the motion of an Components of the static friction force and object traveling in a circular the normal force can contribute to the net path. force producing centripetal acceleration of an object traveling in a circle on a banked surface. 2.9.A.2.iii A component of tension contributes to the net force producing centripetal acceleration experienced by a conical pendulum. 2.9.A.3 Tangential acceleration is the rate at which an object’s speed changes and is directed tangent to the object’s circular path. 2.9.A.4 The net acceleration of an object moving in a circle is the vector sum of the centripetal acceleration and tangential acceleration. 2.9.A.5 The revolution of an object traveling in a circular path at a constant speed (uniform circular motion) can be described using period and frequency. 2.9.A.5.i The time to complete one full circular path, one full rotation, or a full cycle of oscillatory motionisdefinedasperiod,T. 2.9.A.5.ii The rate at which an object is completing revolutionsisdefinedasfrequency,f. Relevant equation: T=1 f 2.9.A.5.iii For an object traveling at a constant speed in a circular path, the period is given by the derived equation continued on next page AP Physics 1: Algebra-Based Course and Exam Description Course Framework V.1 | 61 Return to Table of Contents © 2024 College Board  UNIT 2 Force and Translational Dynamics LEARNING OBJECTIVE ESSENTIAL KNOWLEDGE 2.9.B 2.9.B.1 Describe circular orbits using For a satellite in circular orbit around a central Kepler’s third law. body, the satellite’s centripetal acceleration is caused only by gravitational attraction. The period and radius of the circular orbit are related to the mass of the central body. Derived equation: BOUNDARY STATEMENT AP Physics 1 only expects students to quantitatively analyze banked curves in which no friction is required to maintain uniform circular motion. Analysis of situations in which friction is required on a banked curve is limited to qualitative descriptions. BOUNDARY STATEMENT AP Physics 1 does not expect students to know Kepler’s first or second laws of planetary motion. AP Physics 1: Algebra-Based Course and Exam Description Course Framework V.1 | 62 Return to Table of Contents © 2024 College Board