Summary
Highlights
The session begins with an introduction to the AP Physics 1 exam structure, including the multiple-choice section (50 questions, 1 hour 30 minutes, 50% of score, with 5 multi-select questions requiring two correct answers), and the free-response section (5 questions, 1 hour 30 minutes, focusing on explanations, descriptions, experimental design, qualitative/quantitative translation, and paragraph-length responses). Essential items for the exam, such as calculators (no keyboards, scientific functionality recommended), pencils (regular, not mechanical), and rulers/straight edges for diagrams, are highlighted. The instructor, Christian Herler, introduces himself as an AP Physics reader and table leader, emphasizing the importance of a ruler for clear diagrams. Amanda, CEO of Fiveable, welcomes students and provides information on asking questions through discussion threads for content and chat for tech issues. She also announces a social media contest for sharing cram experiences using #yeswecram and @thinkfiveable for a chance to win $100.
A crucial part of the preparation involves understanding and utilizing the AP Physics 1 equation sheet. Students are advised to cross out sections not covered in the exam, such as electricity, magnetism, waves, and electrostatics. The importance of the math-based help section, including formulas for areas and circumferences, is noted. For gravity, using 10 m/s² instead of 9.8 m/s² is recommended for easier calculations. Specific constants like 'Big G' and 'little G' are highlighted as essential, while others related to charges and masses of subatomic particles are irrelevant. The prefixes (e.g., milli, kilo) and conventions, such as neglecting air resistance unless stated otherwise and defining positive work as work done *on* a system, are also discussed.
This section delves into energy, work, and power. Key equations for potential energy (gravitational and spring), kinetic energy (translational and rotational), work (force parallel to distance), and power are reviewed. The units for most energy forms are Joules, while power is in Watts. The relationship between kinetic energy and momentum ($KE = p^2 / 2m$) is also covered. The work done by friction and conservation of energy are emphasized, noting that the former is not explicitly given on the equation sheet. Force versus displacement graphs are introduced as representing work done. Key concepts include no work being done if force is perpendicular to displacement, the use of energy equations for position-velocity relationships, and work as a transfer of energy. Positive work implies a gain in energy, while negative work indicates energy loss. Examples such as lifting a book illustrate positive and negative work from different perspectives (person vs. gravity). The concept of objects wanting to return to equilibrium is tied to increasing potential energy when moving them away from this state.
A problem involving a block sliding down a frictionless incline from point A to point B is presented. Students are tasked with finding the speed of the block at point B. The solution emphasizes starting with the conservation of energy principle, recognizing that potential energy (mgh) at point A converts to kinetic energy (1/2 mv²) at point B. A common oversight is to use the actual distance traveled along the incline instead of the vertical height for potential energy calculations. The problem is then extended to include friction, requiring students to calculate the work done by friction, which dissipates energy as heat. This involves drawing a free-body diagram to find the normal force (mg cosθ) and using the formula for work done by friction (μFNd). The calculation of the final speed at point B with friction and the subsequent distance the block travels on a flat surface until it stops are detailed.
Momentum is explored, differentiating between translational (linear) and angular momentum. Translational momentum (p = mv) and impulse (J = FΔt = Δp) are discussed, with both sharing the unit of kg·m/s. Angular momentum (L = Iω) and its change (ΔL = τΔt) are introduced. A critical distinction is made between the density equation (ρ = m/V), which can be confused with momentum on the equation sheet due to similar symbols but different meanings and vector nature. Force versus time graphs are highlighted as providing impulse (area under the curve), and the slope of a momentum-time graph gives net force (Newton's second law in its original form). The impulse-momentum theorem (FΔt = mΔv) is emphasized for its application, particularly in scenarios like airbags and helmets, which increase collision time to reduce impact force. Momentum is the preferred method for solving collision problems.
Different types of collisions are categorized: explosions (one object separating into multiple), stick (objects combining and moving together, perfectly inelastic), and bounce (objects separating after impact, elastic or inelastic depending on kinetic energy conservation). Conservation of momentum (P_initial = P_final) is crucial for all collision types, assuming no external forces. Elastic collisions conserve kinetic energy, while inelastic collisions involve a loss of kinetic energy (often as heat or sound). A problem involving a railroad car colliding and sticking to another car is solved, illustrating the application of the conservation of momentum equation (m1v1 + m2v2 = (m1+m2)vf). Another problem on an astronaut pushing off a tank in space (an explosion) demonstrates how momentum is conserved and leads to finding the astronaut's recoil speed. Interactive multiple-choice questions reinforce these concepts, including the effect of sticking on kinetic energy and the application of impulse principles.
Simple Harmonic Motion (SHM) is presented as a significant topic, especially given the removal of other sections from the exam. Key equations on the equation sheet for SHM are identified, including x = A cos(2πft) for position, as well as formulas for the period of a spring (Ts = 2π√(m/k)) and a pendulum (Tp = 2π√(L/g)). The importance of amplitude, spring constant (k), and the dependence of period on mass and spring constant for springs, and length and gravity for pendulums (not mass), are stressed. Concepts such as angular frequency (ω) and total energy conservation within an oscillating system (Et = ½mv² + ½kx² = ½kA²) are discussed. Students are encouraged to use energy conservation alongside SHM equations. Graphs of position, velocity, acceleration, kinetic energy, and potential energy versus time and displacement are analyzed, highlighting their sinusoidal nature and relationships (e.g., kinetic and potential energy are always positive).
Students engage in drawing and interpreting various SHM graphs. They plot momentum vs. time and force vs. time based on given velocity vs. time and acceleration vs. time graphs, respectively. The direct proportionality between momentum and velocity (p=mv) and force and acceleration (F=ma) means their graphs will have similar shapes. Analyzing potential energy vs. time and kinetic energy vs. time graphs reveals their parabolic shapes due to squared terms in their equations and their always non-negative values. The concept of an object being in SHM requires proportional net force to displacement, a sinusoidal motion model, and the period to be independent of amplitude. These criteria help differentiate true SHM from periodic motions that are not simple harmonic, such as a bouncing golf ball. Multiple-choice questions test understanding of period dependencies for pendulums and springs, emphasizing the role of mass, length, and spring constant, and effects of changes in gravity (e.g., on another planet).
FRQs comprise 5 questions over 90 minutes. Two are 12-point questions, and three are short answer. Categories include Quantitative/Qualitative Translation (QQT), experimental design, and paragraph-length response. Students are advised to prioritize questions they feel most confident about. Key terms guide the expected response: 'calculate' requires full work, 'justify/explain' demands prose supported by physics principles or equations. 'Derive' means starting from fundamental equations and showing all steps using given symbols. Strategies for effective graphing (scale, units, ruler for straight lines, smooth curves otherwise, labeling multiple curves, avoiding broken lines) and analyzing graphs (slope, area, outliers) are detailed. Free-body diagram best practices include using a ruler, drawing arrows from the center dot, avoiding component forces on the diagram, and using correct labels (e.g., Fg or mg instead of W, Ff or f for friction, Fs for spring force). Important slopes and areas under common graphs are reviewed, such as velocity from position-time slope and work from force-distance area.
The BCDA method is introduced for paragraph-length responses: Basic physics, Cite evidence, Draw together, and Answer. Starting with basic physics principles (e.g., Newton's laws, conservation laws) is crucial. Citing evidence involves referring to diagrams, data, or comparing scenarios. Drawing together connects physics principles to specific evidence, and finally, directly answering the question. An example of a bouncing ball not returning to its original height is used to illustrate this method. For experimental design questions, the D² (D-square) acronym is presented: Diagram, Setup, Quantities, Apparatus, Repeated Independent Variable, and Error Reduction. Students are encouraged to draw simple, labeled diagrams. The setup involves describing the experiment, including what quantities are measured and with which apparatus. The Repeated Independent Variable section focuses on systematically changing one variable and noting other controls. Error reduction typically involves multiple trials and averaging results. An extended example of designing an experiment to find a toy's spring constant using conservation of energy is walked through, covering diagramming, setup, measurements, and error reduction strategies.
The last hour focuses on MCQ strategies. Students are reminded to use a regular pencil and calculator, and to utilize the equation sheet efficiently. Out of 50 questions, 45 are single-response and 5 are multi-select (requiring two answers). Time management is critical, with approximately 1 minute 48 seconds per question. Key tips include reading questions carefully, circling keywords, drawing pictures for visualization, marking off incorrect answers, and prioritizing easier questions first. Proportional reasoning helps analyze relationships between variables in equations without explicit calculations. Crucially, students are advised not to leave any question blank as there is no penalty for guessing.
Several multiple-choice questions are worked through as a class, covering topics such as kinematics, circular motion, impulse, elastic/inelastic collisions, rotational motion, gravitational force, work, and SHM. These questions are drawn from released AP exams, providing authentic practice. This section includes interactive elements where students choose answers and see their aggregate responses. After a final round of interactive questions, the session concludes with last-minute advice. Students are urged to get sufficient sleep, remain calm, and apply the strategies learned. Shout-outs are given to Brianna (TA), Amanda (CEO), Peter (Science Lead), and the entire Fiveable team for their support. Additional external resources like flippingphysics.com, physicsclassroom.com (Concept Builders), and physicsaviary.com (homework section) are recommended for further practice and review, especially for those taking the exam on a later date. The core message emphasizes confidence and self-care, reminding students that the exam does not define their worth.