SAT2 Physics Core Formulas and High-Frequency Topics | SAT2物理核心公式梳理与高频考点

📚 SAT2 Physics Core Formulas and High-Frequency Topics | SAT2物理核心公式梳理与高频考点

This article systematically organizes the core formulas and high-frequency exam points for the SAT Subject Test in Physics. It is designed to help you review efficiently and target the most commonly tested concepts.

本文系统梳理SAT2物理考试的核心公式和高频考点，帮助你高效复习、精准掌握最常考的概念。

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1. Kinematics and Motion | 运动学与直线运动

Kinematics describes motion without considering forces. The key is to choose the correct equation for constant acceleration.

运动学在不考虑力的情况下描述运动。关键是针对匀加速运动选择正确的公式。

v = u + at

s = ut + ½at²

v² = u² + 2as

• Here u is initial velocity, v is final velocity, a is acceleration, t is time, and s is displacement.

  其中u为初速度，v为末速度，a为加速度，t为时间，s为位移。

• The slope of a position-time graph gives velocity; the slope of a velocity-time graph gives acceleration.

  位移-时间图像的斜率表示速度；速度-时间图像的斜率表示加速度。

• For free fall near Earth’s surface, use a = g = 9.8 m/s² downward.

  地球表面附近自由落体时，取a = g = 9.8 m/s²，方向向下。

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2. Newton’s Laws and Dynamics | 牛顿定律与动力学

Newton’s laws connect force and motion. Free-body diagrams are essential for solving problems.

牛顿定律将力与运动联系起来。受力分析图是解题的关键。

F_net = ma

F_friction = μN

• Newton’s first law: an object stays at rest or moves at constant velocity unless acted on by a net force.

  牛顿第一定律：物体在不受合力作用时保持静止或匀速直线运动。

• Newton’s third law: every action has an equal and opposite reaction.

  牛顿第三定律：作用力与反作用力大小相等、方向相反。

• Normal force N is perpendicular to the surface; friction μN is parallel to the surface and opposes motion.

  支持力N垂直于接触面；摩擦力μN平行于接触面并阻碍运动。

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3. Work, Energy, and Power | 功、能量与功率

Energy conservation is a powerful tool. Work transforms energy from one form to another.

能量守恒是强有力的工具。做功使能量在不同形式间转化。

W = Fd cosθ

KE = ½mv²

PE_gravity = mgh

P = W/t

• Work is done when a force causes displacement. θ is the angle between force and displacement.

  力使物体发生位移时做功。θ为力与位移之间的夹角。

• Kinetic energy equals ½mv²; gravitational potential energy near Earth is mgh.

  动能等于½mv²；地球表面附近的重力势能为mgh。

• Power is the rate of doing work. In the SI system, 1 watt = 1 joule/second.

  功率是做功的快慢。在国际单位制中，1瓦特 = 1焦耳/秒。

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4. Momentum and Collisions | 动量与碰撞

Momentum is conserved in isolated systems. Collisions are classified as elastic or inelastic.

孤立系统中动量守恒。碰撞分为弹性碰撞和非弹性碰撞。

p = mv

J = Δp = FΔt

• Total momentum before a collision equals total momentum after the collision.

  碰撞前后总动量相等。

• In an elastic collision, both momentum and kinetic energy are conserved.

  弹性碰撞中，动量和动能均守恒。

• In a perfectly inelastic collision, the objects stick together; kinetic energy is not conserved.

  完全非弹性碰撞中，物体粘在一起；动能不守恒。

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

Objects moving in a circle accelerate toward the center. Gravity provides the centripetal force for orbits.

做圆周运动的物体具有指向圆心的加速度。万有引力为轨道运动提供向心力。

a_c = v²/r

F_c = mv²/r

F_gravity = GMm/r²

• Centripetal force is not a new force; it is the net force pointing toward the center of the circle.

  向心力不是新力，而是指向圆心的合力。

• Newton’s law of universal gravitation: G = 6.67 × 10⁻¹¹ N·m²/kg².

  万有引力定律中，G = 6.67 × 10⁻¹¹ N·m²/kg²。

• For a satellite in circular orbit, GMm/r² = mv²/r, giving orbital speed v = √(GM/r).

  对于圆形轨道上的卫星，GMm/r² = mv²/r，可得轨道速度v = √(GM/r)。

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6. Electrostatics and Circuits | 静电学与电路

Electric charges create forces and fields. Circuits follow Ohm’s law and conservation of energy.

电荷产生力与电场。电路遵循欧姆定律和能量守恒。

F = kq₁q₂/r²

E = F/q

V = IR

P = IV

• Coulomb’s law: k = 8.99 × 10⁹ N·m²/C². Like charges repel, unlike charges attract.

  库仑定律：k = 8.99 × 10⁹ N·m²/C²。同种电荷相斥，异种电荷相吸。

• Electric field E points from positive to negative; potential difference V = W/q.

  电场方向从正电荷指向负电荷；电势差V = W/q。

• In a series circuit, resistances add; in a parallel circuit, their reciprocals add.

  串联电路中电阻相加；并联电路中电阻倒数相加。

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7. Magnetism and Electromagnetism | 磁学与电磁感应

Moving charges create magnetic fields. Changing magnetic flux induces electromotive force.

运动的电荷产生磁场。变化的磁通量感应出电动势。

F = qvB sinθ

F = BIL sinθ

emf = -N ΔΦ/Δt

• The magnetic force on a moving charge is perpendicular to both velocity and field.

  运动电荷所受磁场力同时垂直于速度和磁场方向。

• Faraday’s law: induced emf equals the negative rate of change of magnetic flux times number of loops.

  法拉第定律：感应电动势等于磁通量变化率的负值乘以线圈匝数。

• Lenz’s law states the induced current opposes the change in flux.

  楞次定律指出感应电流的方向阻碍磁通量的变化。

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8. Waves and Optics | 波动与光学

Waves transfer energy without transferring matter. Light exhibits both wave and particle properties.

波传递能量但不传递物质。光具有波动性和粒子性。

v = fλ

n₁ sinθ₁ = n₂ sinθ₂

1/f = 1/d₀ + 1/dᵢ

• Wave speed equals frequency times wavelength. For light in vacuum, v = c = 3 × 10⁸ m/s.

  波速等于频率乘以波长。真空中光速v = c = 3 × 10⁸ m/s。

• Snell’s law governs refraction. Total internal reflection occurs when the incident angle exceeds the critical angle.

  斯涅尔定律描述折射。当入射角超过临界角时发生全反射。

• Thin lens equation: focal length f is positive for converging lens, negative for diverging lens.

  薄透镜公式：会聚透镜焦距f为正，发散透镜焦距f为负。

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9. Thermal Physics | 热学

Temperature, heat, and energy transfer are core thermal concepts. The ideal gas law is frequently tested.

温度、热量和能量传递是热学核心概念。理想气体定律是高频考点。

Q = mcΔT

PV = nRT

ΔU = Q – W

• Specific heat capacity c is the heat needed to raise 1 kg of a substance by 1°C.

  比热容c指使1千克物质升高1°C所需的热量。

• Ideal gas law: R = 8.31 J/(mol·K). Temperature must be in kelvin.

  理想气体定律：R = 8.31 J/(mol·K)。温度必须用开尔文。

• First law of thermodynamics: change in internal energy equals heat added minus work done by the gas.

  热力学第一定律：内能变化等于吸收的热量减去气体对外做的功。

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10. Modern Physics | 现代物理

Quantum mechanics and relativity introduced revolutionary ideas. Photons and atomic transitions are common topics.

量子力学和相对论带来了革命性观念。光子和原子跃迁是常见考点。

E = hf

E = mc²

λ = h/p

• Photon energy E = hf, where h = 6.63 × 10⁻³⁴ J·s.

  光子能量E = hf，其中h = 6.63 × 10⁻³⁴ J·s。

• Mass-energy equivalence: a small amount of mass corresponds to a huge amount of energy.

  质能方程：微小质量对应巨大能量。

• De Broglie wavelength: particles also have wave-like behavior. This is tested in electron diffraction contexts.

  德布罗意波长：粒子也具有波动性。常在电子衍射情景中考查。

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