📚 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。
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。
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。
Fnet = 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。
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。
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。
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。
ac = v²/r
Fc = 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。
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。
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。
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。
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。
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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