SAT2 Physics: Key Concepts Summary and Exam Preparation Guide | SAT2物理：考点总结与备考指南

📚 SAT2 Physics: Key Concepts Summary and Exam Preparation Guide | SAT2物理：考点总结与备考指南

The SAT Subject Test in Physics was once a widely recognized exam for demonstrating college readiness in science. Although the College Board discontinued all SAT Subject Tests in 2021, the content coverage remains highly relevant for AP Physics, college-level introductory physics, and even engineering entrance preparation. This guide distills the core topics tested, from mechanics to modern physics, and offers targeted study strategies. Use it to build a robust conceptual foundation and tackle physics problems with confidence.

SAT2物理学科考试曾是美国大学申请中证明理科能力的重要考试。尽管美国大学理事会已于2021年取消所有SAT学科考试，但其覆盖的知识点仍是AP物理、大学基础物理乃至理工科入学准备的宝贵基础。本文提炼了力学、电磁学、波动光学、热学与现代物理等核心考点，并提供高效备考策略，帮助你构建扎实的物理概念体系，自信应对各类物理问题。

1. Kinematics and Motion Graphs | 运动学与运动图像

Kinematics describes motion without considering its causes. You must master the relationships among displacement, velocity, acceleration, and time. Be comfortable interpreting position-time and velocity-time graphs, as many SAT2 questions test your ability to extract information directly from these visuals. The four kinematic equations for constant acceleration are essential, but symbolic manipulation and proportionality thinking often matter more than number crunching.

运动学描述运动而不追究原因。你需要熟练掌握位移、速度、加速度与时间的关系，并善于解读位置-时间图和速度-时间图，因为很多SAT2题目直接考查从图像中提取信息的能力。四个匀变速直线运动方程是基础，但符号推导和比例思维往往比代入数字更重要。

Displacement vs distance: displacement is a vector; distance is scalar. Average velocity = total displacement / time.
位移与路程：位移是矢量，路程是标量。平均速度 = 总位移/时间。
Constant acceleration equations: v = v₀ + at, s = v₀t + ½at², v² = v₀² + 2as. Stay aware of sign conventions.
匀变速方程：v = v₀ + at, s = v₀t + ½at², v² = v₀² + 2as。务必注意方向符号的规定。
Slope of position-time graph gives velocity; slope of velocity-time graph gives acceleration; area under v-t graph is displacement.
位置-时间图斜率表示速度；速度-时间图斜率表示加速度；v-t图下面积表示位移。

2. Newton’s Laws and Free-Body Diagrams | 牛顿定律与受力分析

Newton’s three laws form the backbone of classical mechanics. You need to identify forces acting on an object, draw accurate free-body diagrams, and apply F = ma in vector form. Questions often involve inclined planes, tension in ropes, and friction. Distinguish static and kinetic friction, and never forget that Newton’s third law pairs act on different bodies.

牛顿三定律是经典力学的骨架。你必须能识别物体受力，画出准确的受力分析图，并用矢量形式F = ma列方程。常见题型包括斜面、绳中张力与摩擦力。注意区分静摩擦与滑动摩擦，切记牛顿第三定律的作用力与反作用力作用在不同物体上。

First law: inertia; an object maintains its state of motion unless a net external force acts. Direct application in equilibrium problems.
第一定律：惯性；不受净外力时物体保持原运动状态。常用于平衡问题。
Second law: ΣF = ma. Remember net force is the vector sum; solve in perpendicular components.
第二定律：ΣF = ma。净外力为矢量和，通常在相互垂直方向上分解求解。
Third law: F_AB = -F_BA. They are equal in magnitude, opposite in direction, but act on different objects.
第三定律：F_AB = -F_BA。大小相等、方向相反，但作用在不同物体上。
Friction: static friction 0 ≤ f_s ≤ μ_s N; kinetic friction f_k = μ_k N. Friction always opposes relative motion or tendency.
摩擦力：静摩擦 0 ≤ fₛ ≤ μₛN；动摩擦 fₖ = μₖN。摩擦力总是阻碍相对运动或相对运动趋势。

3. Work, Energy, and Power | 功、能与功率

The work-energy theorem connects force and motion elegantly. Work is done only when a force has a component parallel to displacement. Kinetic energy (½mv²) changes by the net work done. Potential energy appears when conservative forces do work: gravitational PE = mgh near Earth’s surface, elastic PE = ½kx². Power is the rate of work, often linked with force and velocity: P = Fv cosθ.

功能定理将力与运动巧妙结合。只有力在位移方向上有分量时该力才做功。动能(½mv²)的变化等于合外力做的功。保守力做功时出现势能：重力势能PE = mgh（近地表），弹性势能PE = ½kx²。功率为做功的快慢，经常与力和速度关联：P = Fv cosθ。

W = F d cosθ KE = ½mv² PE_gravity = mgh PE_spring = ½kx² P = W / t = F v cosθ

Energy conservation is a favorite SAT2 problem-solving tool. In isolated systems with only conservative forces, total mechanical energy is constant. Even with non-conservative forces, you can track energy dissipation with W_nc = ΔE.

能量守恒是SAT2最喜欢的解题工具。在只有保守力的孤立系统中，总机械能保持不变。即使存在非保守力，也可以利用非保守力做功等于机械能变化来追踪能量耗散。

4. Momentum and Collisions | 动量与碰撞

Momentum is always conserved in collisions when no external net force acts, regardless of whether kinetic energy is conserved. Master the impulse-momentum theorem, which connects force over time to momentum change. Distinguish elastic collisions (both momentum and KE conserved) from inelastic collisions (momentum conserved, KE not conserved) and perfectly inelastic collisions (objects stick together).

只要系统合外力为零，碰撞中动量总是守恒的，与动能是否守恒无关。要掌握冲量定理，它将力在时间上的累积与动量变化联系起来。区分弹性碰撞（动量和动能都守恒）、非弹性碰撞（动量守恒，动能减少）和完全非弹性碰撞（碰后粘在一起）。

p = mv J = FΔt = Δp Σp_initial = Σp_final

For two-body head-on elastic collisions, relative speed of approach equals relative speed of separation. This shortcut often avoids heavy algebra. In perfectly inelastic cases, find final common velocity by conservation of momentum only.

对于两体正碰弹性碰撞，接近时相对速度等于分离时相对速度。这一捷径常常能避开繁复代数运算。完全非弹性碰撞中，仅用动量守恒即可求出共同速度。

5. Circular Motion and Gravitation | 圆周运动与万有引力

Uniform circular motion requires a centripetal force directed toward the center, not a separate “new” force but a net inward force provided by tension, gravity, friction, or normal force. The centripetal acceleration is a_c = v²/r = ω²r. In orbital mechanics, gravity supplies this centripetal force, leading to Kepler’s laws and satellite velocity. Newton’s law of universal gravitation is F = Gm₁m₂/r², with field g = GM/r² at distance r from a planet’s center.

匀速圆周运动需要指向圆心的向心力，它不是一种“新”力，而是由拉力、引力、摩擦力或支持力提供的净向心力。向心加速度a_c = v²/r = ω²r。在天体运动中，万有引力提供向心力，由此得出开普勒定律与卫星速度。万有引力定律为F = Gm₁m₂/r²，距行星中心r处的引力场强为g = GM/r²。

a_c = v² / r = ω²r F_c = m a_c F_g = G m₁ m₂ / r² v_orb = √(GM/r)

Gravitational potential energy far from a planet is U = -GMm/r, distinct from mgh. The total mechanical energy of an orbiting satellite is negative and equals half the gravitational potential energy (E = -GMm/(2r)).

远离天体表面的引力势能为U = -GMm/r，区别于mgh。绕行卫星的总机械能为负，等于引力势能的一半(E = -GMm/(2r))。

6. Electrostatics and Electric Fields | 静电学与电场

Coulomb’s law governs the force between point charges: F = k|q₁q₂|/r². The electric field is force per unit test charge: E = F/q = kQ/r² for a point charge. Electric field lines begin on positive charges and end on negative charges. Potential difference V is the work per unit charge done by the electric field; equipotential surfaces are always perpendicular to field lines. For uniform fields, V = Ed.

库仑定律描述点电荷间作用力：F = k|q₁q₂|/r²。电场强度是单位试探电荷所受的力：E = F/q, 点电荷场强E = kQ/r²。电场线起于正电荷，止于负电荷。电势差V是移动单位电荷电场力做的功；等势面恒与电场线垂直。匀强电场中V = Ed。

F = k q₁ q₂ / r² E = F / q = k Q / r² V = k Q / r U = qV

Conductors in electrostatic equilibrium have zero electric field inside and charge resides on the outer surface. Understand the motion of a charged particle in a uniform electric field, analogous to projectile motion but with constant electric force instead of gravity.

静电平衡下的导体内部电场为零，电荷分布在导体外表面。要理解带电粒子在匀强电场中的运动，它与抛体运动类似，只是恒力由电场力替代了重力。

7. Circuits and Ohm’s Law | 电路与欧姆定律

Direct current circuits require a solid grasp of Ohm’s law (V = IR), resistance, resistivity (R = ρL/A), and power dissipated (P = IV = I²R = V²/R). Series circuits have the same current, dividing voltage; parallel circuits share voltage, dividing current. Simplify resistor networks stepwise. Know how to read ammeter (series) and voltmeter (parallel) placements. Internal resistance of real batteries causes terminal voltage to drop under load.

直流电路需要扎实掌握欧姆定律(V = IR)、电阻与电阻率(R = ρL/A)以及功率耗散(P = IV = I²R = V²/R)。串联电路电流相同、分压；并联电路电压相同、分流。逐步化简电阻网络。要知道电流表应串联、电压表应并联。实际电池的内阻会导致路端电压随电流增大而下降。

Series	Parallel
R_eq = R₁ + R₂ + …	1/R_eq = 1/R₁ + 1/R₂ + …
Same current (I)	Same voltage (V)
Voltage divides: V_total = V₁+V₂	Current divides: I_total = I₁+I₂

Kirchhoff’s junction rule (ΣI_in = ΣI_out) and loop rule (ΣΔV = 0) are the ultimate fallback for complex circuits. Capacitors in DC circuits block steady current once fully charged; time-dependent behavior is rarely tested but basic RC time constant τ = RC may appear.

基尔霍夫电流定律(ΣI进 = ΣI出)和电压定律(ΣΔV = 0)是复杂电路的终极法宝。电容器在直流电路中充电结束后相当于断路；暂态过程很少考，但时间常数τ = RC的基本概念可能涉及。

8. Magnetism and Electromagnetic Induction | 磁场与电磁感应

Magnetic fields exert forces on moving charges and current-carrying wires. The magnitude is F = qvB sinθ for a charge and F = BIL sinθ for a straight wire. The direction is given by the right-hand rule (for a positive charge). Circular motion of a charged particle in a uniform B-field has radius r = mv/(qB). Be able to determine the magnetic field direction due to a straight current (right-hand grip rule) and inside a solenoid.

磁场对运动电荷和载流导线有力的作用。电荷受力大小 F = qvB sinθ，直导线受力 F = BIL sinθ，方向由右手定则（对正电荷）判断。带电粒子在匀强磁场中做匀速圆周运动，半径 r = mv/(qB)。要会用右手螺旋定则判断长直电流和螺线管内部的磁场方向。

Electromagnetic induction is governed by Faraday’s law: induced emf ε = -N ΔΦ/Δt, where Φ = BA cosθ. Lenz’s law determines the direction of induced current: it opposes the change in magnetic flux. Motional emf for a conductor moving perpendicularly in a field is ε = Blv.

电磁感应由法拉第定律支配：感应电动势 ε = -N ΔΦ/Δt，其中 Φ = BA cosθ。楞次定律判断感应电流方向：感应电流的磁场总要阻碍引起感应的磁通量变化。导线在磁场中垂直切割磁感线产生的动生电动势为 ε = Blv。

9. Waves and Sound | 波动与声波

Waves transfer energy without transferring matter. Distinguish transverse (e.g., string) from longitudinal (e.g., sound) waves. Key quantities: frequency f, period T = 1/f, wavelength λ, and wave speed v = fλ. The speed of a wave on a string depends on tension and linear density; sound speed depends on medium and temperature. Be familiar with reflection, refraction, diffraction, and the principle of superposition.

波传播能量而不传播物质。区分横波（如弦波）和纵波（如声波）。关键物理量：频率 f、周期 T = 1/f、波长 λ 及波速 v = fλ。弦上的波速取决于张力和线密度；声速取决于介质和温度。要熟悉反射、折射、衍射及叠加原理。

Standing waves on a string or in a pipe produce harmonic patterns. For a string fixed at both ends, λ_n = 2L/n, f_n = n f_1. For open pipes, both ends are antinodes; for closed pipes, one end is a node. Beat frequency equals the difference in frequencies: f_beat = |f₁ – f₂|. The Doppler effect for sound yields observed frequency f’ = f (v ± v_o)/(v ± v_s). Choose signs by considering relative motion toward or away.

弦或管中的驻波形成谐波模式。两端固定的弦，λₙ = 2L/n, fₙ = n f₁。开管两端为波腹；闭管一端为波节。拍频等于两波频率之差：f_beat = |f₁ – f₂|。多普勒效应中，观察频率 f’ = f (v ± vₒ)/(v ± vₛ)，根据观察者与声源相对靠近或远离选取符号。

10. Optics and Light | 光学与光

Geometric optics relies on ray diagrams for mirrors and lenses. The mirror and lens equation (1/f = 1/d_o + 1/d_i) and magnification m = -d_i/d_o are essential. Sign conventions depend on the system: for mirrors, f = R/2, with positive f for concave; for lenses, converging lenses have positive f. Be able to locate images and determine whether they are real/virtual, upright/inverted, and enlarged/reduced.

几何光学依赖于面镜和透镜的光线图。透镜/面镜公式(1/f = 1/dₒ + 1/dₑ)和放大率 m = -dₑ/dₒ非常重要。符号规定：面镜的焦距 f = R/2，凹面镜 f 为正；凸透镜（会聚透镜）f 为正。要能确定像的位置，判断实像/虚像、正立/倒立、放大/缩小。

Refraction obeys Snell’s law: n₁ sinθ₁ = n₂ sinθ₂. Index of refraction n = c/v. Total internal reflection occurs when light travels from higher to lower index and incidence angle exceeds critical angle θ_c = sin⁻¹(n₂/n₁). Dispersion explains white light splitting into colors. Young’s double-slit interference gives bright fringes at d sinθ = mλ; single-slit minima at a sinθ = mλ.

折射遵循斯涅尔定律：n₁ sinθ₁ = n₂ sinθ₂，折射率 n = c/v。当光从光密介质射向光疏介质，且入射角超过临界角θ_c = sin⁻¹(n₂/n₁)时发生全内反射。色散解释了白光分解为颜色。杨氏双缝干涉亮纹满足 d sinθ = mλ；单缝衍射暗纹满足 a sinθ = mλ。

11. Thermal Physics and Ideal Gases | 热物理学与理想气体

Temperature measures average kinetic energy of particles. Convert between Celsius and Kelvin: K = °C + 273. Heat is energy transferred due to temperature difference; specific heat capacity Q = mcΔT and latent heat Q = mL govern phase changes without temperature change. Thermal expansion of solids: ΔL = α L₀ ΔT.

温度是粒子平均动能的量度。摄氏与开尔文换算：K = °C + 273。热是温度差引起的能量传递；比热容 Q = mcΔT，相变时潜热 Q = mL 而温度不变。固体热膨胀：ΔL = α L₀ ΔT。

The ideal gas law PV = nRT = NkT connects pressure, volume, temperature, and amount. In kinetic theory, average translational kinetic energy per molecule is (3/2)kT. The gas laws (Boyle’s, Charles’s, Gay-Lussac’s) are special cases. The first law of thermodynamics ΔU = Q – W (work done BY system is positive) ties internal energy, heat, and work. Key processes: isothermal (ΔU=0, Q=W), adiabatic (Q=0, ΔU=-W), isochoric (W=0), isobaric (W=PΔV).

理想气体定律 PV = nRT = NkT 联结压强、体积、温度与物质的量。分子动理论中，每个分子平均平动动能是 (3/2)kT。气体实验定律（波义耳、查理、盖-吕萨克定律）是特例。热力学第一定律 ΔU = Q – W（系统对外做功W为正）将内能、热量和功联系起来。重点过程：等温(ΔU=0, Q=W)、绝热(Q=0, ΔU=-W)、等容(W=0)、等压(W=PΔV)。

12. Modern Physics: Quantum, Atomic, and Nuclear | 现代物理：量子、原子与核物理

Modern physics questions are often conceptual but contain important equations. Photon energy E = hf; photoelectric effect requires understanding that KE_max = hf – φ, where φ is the work function. Energy levels in atoms are quantized; photon absorption/emission corresponds to energy differences ΔE. The Bohr model gives discrete orbital radii with angular momentum quantized, though simply knowing the hydrogen spectrum patterns helps.

现代物理多考概念，但含有重要公式。光子能量 E = hf；光电效应要掌握最大动能 KE_max = hf – φ，φ是逸出功。原子能级是量子化的；吸收/发射光子的能量对应能级差 ΔE。玻尔模型给出分立轨道半径及角动量量子化，熟悉氢原子光谱规律即可。

E = hf KE_max = hf – φ ΔE = hf λ = h / p (de Broglie)

Nuclear physics: know alpha, beta, gamma decay properties; radioactive decay law and half-life. Mass–energy equivalence E = mc² explains mass defect and binding energy. In nuclear reactions, conservation of mass number and charge must hold. Familiarity with fission, fusion, and the strong nuclear force is beneficial.

核物理：了解α、β、γ衰变特性；放射性衰变定律与半衰期。质能方程 E = mc² 解释了质量亏损与结合能。核反应中质量数和电荷数守恒。了解裂变、聚变及强核力基本概念。

13. Test-Taking Strategies and Review Tips | 备考策略与复习技巧

Mastering SAT2 Physics requires more than memorization. Develop a strong conceptual understanding first, then practice with realistic problems. Focus on proportional reasoning: many questions test how changing one variable affects another without numbers. Time management is crucial; you must answer about 75 multiple-choice questions in 60 minutes, so pace yourself and skip extremely long calculations.

征服SAT2物理不仅靠记忆。先建立扎实的概念理解，再用实际题目练习。重点训练比例推理：很多题不需要具体数值，只问当一个变量改变时其他量如何变化。时间管理至关重要，约75道选择题需在60分钟内完成，掌控节奏，跳过极耗时的计算。

Always analyze answer choices after reading the stem: eliminate obviously wrong options using dimensions, extreme cases, or symmetry. When a problem involves multiple concepts, break it into familiar steps. In the final weeks, review your formula sheet daily and drill the most frequent graph interpretations (kinematics, energy, waves, circuits).

读题后先分析选项，利用量纲、极端情形或对称性排除明显错误答案。遇到综合题，分解为你熟悉的步骤。临考几周，每日复习公式表，并强化最常见图形解读题（运动学、能量、波动、电路）。

Though the SAT Subject Test is no longer offered, treating this syllabus as a mini-AP review can sharpen your physics intuition and problem-solving agility. Every concept you reinforce here pays off in higher-level courses.

尽管SAT学科考试已不再举办，将这份考纲作为一份迷你AP物理复习指南，可有效提升你的物理直觉与解题敏捷度。你在此强化的每一个概念，都将在后续高阶课程中获得回报。

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SAT2 Physics: Key Concepts Summary and Exam Preparation Guide | SAT2物理：考点总结与备考指南