📚 Year 9 Cambridge Physics: Vocabulary Quick-Memory Guide | 剑桥Year 9物理：词汇术语速记指南
Welcome to your essential guide for mastering key physics vocabulary for Year 9 Cambridge Lower Secondary Science. Understanding these terms is the first step to solving problems and explaining concepts clearly. This bilingual revision resource provides concise definitions in both English and Chinese, designed to help you memorise and apply each term with confidence.
欢迎阅读 Year 9 剑桥初中科学物理核心术语速记指南。掌握这些术语是解题和清晰解释概念的第一步。这份双语复习材料用中英文提供简明定义，帮助你自信地记忆并应用每个术语。
1. Forces and Their Effects | 力及其作用
Force: A force is a push or a pull acting on an object. It can change an object's speed, direction or shape. Force is a vector quantity and is measured in newtons (N).
力：力是作用在物体上的推或拉。它可以改变物体的速度、方向或形状。力是矢量，单位为牛顿 (N)。
Contact force: A contact force acts when two objects touch each other. Examples include friction, air resistance and tension. These forces oppose motion or transmit pulls through strings.
接触力：接触力在两个物体接触时产生。例如摩擦力、空气阻力和拉力。这些力通常阻碍运动或通过绳子传递拉力。
Non-contact force: A non-contact force acts at a distance without physical contact. Gravity, magnetic force and electrostatic force are common examples. Weight is the non-contact force due to gravity.
非接触力：非接触力无需接触就能在空间中作用。常见的例子有引力、磁力和静电力。重量就是由于引力产生的一种非接触力。
Weight: ational field strength: W = m × g. Weight is measured in newtons and varies with location.
重量：重量是物体受到的引力。它取决于质量和引力场强度：W = m × g。重量以牛顿为单位，并随位置变化。
Resultant force: The resultant force is the single force that has the same effect as all the forces acting together. If resultant force is zero, forces are balanced and motion stays constant. An unbalanced resultant causes acceleration.
合力：合力是能产生与所有作用力相同效果的一个单独力。若合力为零，力平衡，运动状态不变；合力不为零则产生加速度。
2. Motion and Graphs | 运动与图像
Speed: r quantity, calculated as speed = distance ÷ time. The SI unit is metres per second (m/s).
速率：速率是距离变化的快慢，是标量，计算公式为速率 = 距离 ÷ 时间。国际单位是米每秒 (m/s)。
Velocity: Velocity is speed in a given direction. It is a vector quantity. Constant velocity means steady speed in a straight line; changing velocity implies acceleration.
速度：速度是带有方向的速率，是矢量。匀速意味着沿直线以稳定快慢运动；速度变化就意味着有加速度。
Acceleration: Acceleration is the rate of change of velocity. It is calculated as change in velocity ÷ time taken. Negative acceleration means deceleration or slowing down.
加速度：加速度是速度变化的快慢，计算公式为速度变化量 ÷ 时间。负加速度表示减速。
Distance-time graph: A graph with distance on the y-axis and time on the x-axis. A straight sloping line indicates constant speed; a horizontal line means the object is stationary. The gradient equals speed.
距离-时间图：纵轴为距离，横轴为时间。倾斜的直线表示匀速运动；水平线表示静止。斜率代表速率。
Speed-time graph: A graph with speed on the y-axis and time on the x-axis. The gradient gives acceleration. A horizontal line shows constant speed, and the area under the line represents distance travelled.
速率-时间图：纵轴为速率，横轴为时间。斜率代表加速度，水平线表示匀速，图线下方的面积表示走过的距离。
3. Energy Forms and Transfer | 能量形式与转化
Kinetic energy: Kinetic energy is the energy an object possesses due to its motion. The faster an object moves and the greater its mass, the more kinetic energy it has. It is measured in joules (J).
动能：动能是物体由于运动而具有的能量。物体运动越快、质量越大，动能越大。单位为焦耳 (J)。
Gravitational potential energy: due to its position above the ground. GPE = mass × gravitational field strength × height.
重力势能：重力势能是物体因离地高度而储存的能量。GPE = 质量 × 引力场强度 × 高度。
Energy transfer: Energy can be transferred from one store to another by forces, heating, or waves. For example, a moving ball transfers kinetic energy to sound and thermal energy upon impact.
能量转移：能量可以通过力、加热或波的形式从一个储存转移到另一个。例如运动的球碰撞后将动能转化为声能和热能。
Conservation of energy: Energy cannot be created or destroyed, only transferred or converted from one form to another. The total energy in a closed system remains constant.
能量守恒：能量不能被创造或消灭，只能被转移或从一种形式转化为另一种。封闭系统中总能量保持不变。
Thermal energy: Thermal energy is the total kinetic and potential energy of the particles in a substance. Heat flows from hotter to cooler objects until thermal equilibrium is reached.
热能：热能是物质粒子总动能和势能的总和。热从高温物体流向低温物体，直至达到热平衡。
4. Work, Power and Efficiency | 功、功率与效率
Work done: Work = force × distance moved in the direction of the force. It is measured in joules (J).
做功：当一个力使物体沿力的方向移动时，该力做了功。功 = 力 × 沿力方向移动的距离，单位为焦耳 (J)。
Power: rring energy. Power = work done ÷ time taken. The unit is the watt (W), where 1 W = 1 J/s.
功率：功率是做功或能量转移的快慢。功率 = 做功 ÷ 时间。单位是瓦特 (W)，1 W = 1 J/s。
Efficiency: : Efficiency measures how much useful energy or work output is obtained from the total input. Efficiency = (useful output ÷ total input) × 100%. No device is 100% efficient due to energy losses, usually as thermal energy.
效率：效率衡量获得的有用能量或输出功占总输入的比例。效率 = (有用输出 ÷ 总输入) × 100%。由于能量损失（通常是热能），没有设备能达到100%效率。
5. Waves: Sound and Light | 波：声与光
Transverse wave: In a transverse wave, the vibrations are perpendicular to the direction of energy transfer. Light and water waves are transverse. They show crests and troughs.
横波：横波中，振动方向与能量传递方向垂直。光波和水波是横波，显示波峰和波谷。
Longitudinal wave: In a longitudinal wave, the vibrations are parallel to the direction of energy transfer. Sound waves are longitudinal, consisting of compressions and rarefactions.
纵波：纵波中，振动方向与能量传递方向平行。声波是纵波，由压缩区和稀疏区组成。
Amplitude: Amplitude is the maximum displacement of a point on a wave from its rest position. For sound, greater amplitude means louder volume; for light, it relates to brightness.
振幅：振幅是波上某点离开平衡位置的最大位移。对声音而言，振幅越大声音越响；对光而言，它与亮度相关。
Frequency: Frequency is the number of complete waves passing a point per second. It is measured in hertz (Hz). High frequency sound gives a high pitch; high frequency light appears towards the violet end of the spectrum.
频率：频率是每秒通过某点的完整波的数量，单位为赫兹 (Hz)。高频声音音调高，高频光靠近光谱紫端。
Refraction: Refraction is the change in direction of a wave when it enters a new medium at an angle, due to a change in wave speed. A light ray bends towards the normal when slowing down.
折射：折射是波因速度变化、倾斜进入新介质时方向改变的现象。光慢下来时偏向法线折射。
6. Electricity | 电
Current: Electric current is the flow of electric charge. In a metal wire, it is the movement of electrons. Current (I) is measured in amperes (A), using an ammeter connected in series.
电流：电流是电荷的流动。在金属导线中，它是电子的定向移动。电流 (I) 以安培 (A) 为单位，用串联的安培计测量。
Voltage: Voltage (potential difference) is the energy transferred per unit charge between two points in a circuit. It drives the current and is measured in volts (V) with a voltmeter connected in parallel.
电压：电压（电势差）是电路中两点间每单位电荷转移的能量。它驱动电流，单位为伏特 (V)，用并联的伏特计测量。
Resistance: Resistance opposes the flow of current. It is measured in ohms (Ω). Ohm' R for a resistor at constant temperature. A longer or thinner wire has higher resistance.
电阻：电阻阻碍电流流动，单位为欧姆 (Ω)。欧姆定律指出恒温下电阻器满足 V = I × R。更长或更细的导线电阻更大。
Series circuit: In a series circuit, components are connected end-to-end. The current is the same everywhere. The total resistance is the sum of individual resistances. If one component fails, the circuit breaks.
串联电路：串联电路中元件依次连接，各处电流相等。总电阻等于各电阻之和。若一个元件断开，整个电路断开。
Parallel circuit: In a parallel circuit, components are connected across separate branches. The voltage across each branch is the same. The total current is the sum of branch currents. A break in one branch does not stop others.
并联电路：并联电路中元件跨接在不同的支路上，各支路电压相同。总电流为各支路电流之和。一条支路断开不影响其他支路。
7. Magnetism and Electromagnetism | 磁与电磁
Magnetic field: A magnetic field is a region around a magnet where magnetic forces act. Field lines point from the north pole to the south pole outside a magnet. Closer lines indicate a stronger field.
磁场：磁场是磁体周围有磁力作用的区域。磁体外部的磁感线从北极指向南极。磁感线越密，磁场越强。
Electromagnet: An electromagnet is a coil of wire (solenoid) that acts as a magnet when current flows through it. Increasing the current or adding a soft iron core makes it stronger. It loses magnetism when the current stops.
电磁铁：电磁铁是通电时产生磁性的线圈（螺线管）。增大电流或加入软铁芯可增强磁性，断电后磁性消失。
Permanent magnet: A permanent magnet retains its magnetism without an external current. It has fixed north and south poles. Hard magnetic materials like steel are used.
永磁体：永磁体不需外部电流就能保持磁性，有固定的南北极，常用钢等硬磁材料制成。
Induced magnetism: When a magnetic material is placed in a magnetic field, it becomes a temporary magnet. This induced magnetism is always attractive. Soft iron loses its magnetism quickly when removed from the field.
感应磁性：将磁性材料放入磁场中，它会变成暂时磁体。这种感应磁性总是吸引。软铁移出磁场后很快失去磁性。
8. Thermal Physics | 热物理
Conduction: Conduction is the transfer of thermal energy through a solid by particle vibrations and free electron movement. Metals are good conductors, while non-metals and gases are poor conductors (insulators).
热传导：热传导是通过粒子振动和自由电子移动在固体中传递热能的方式。金属是良导体，非金属和气体是热的不良导体（绝缘体）。
Convection: Convection occurs in fluids (liquids and gases) where warmer, less dense regions rise and cooler, denser regions sink, forming a convection current.
热对流：对流发生在流体（液体和气体）中，较热、密度较小的区域上升，较冷、密度较大的区域下沉，形成对流循环。
Radiation: Thermal radiation is the transfer of energy by infrared electromagnetic waves. It does not require a medium and can travel through a vacuum. Dull black surfaces are good absorbers and emitters; shiny silver surfaces are poor
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