📚 AS AQA Mechanics Topic Test: Complete Revision Guide | AS AQA 力学主题测试:完整复习指南
This comprehensive revision guide covers every core topic in the OxfordAQA International AS Mathematics 9660 Mechanics syllabus. Each section pairs English explanations with Chinese translations, giving you a bilingual pathway to mastering kinematics, forces, momentum and energy for your topic tests.
本复习指南涵盖牛津AQA国际AS数学9660力学大纲中的所有核心主题。每一节均配有中英文对照讲解,为你提供掌握运动学、力、动量与能量的双语学习路径,助你从容应对主题测试。
1. Kinematics: Displacement, Velocity and Acceleration | 运动学:位移、速度与加速度
Kinematics describes motion without considering its causes. Displacement (s) is a vector quantity measured in metres (m), representing the change in position from a fixed origin. Speed is scalar, while velocity (v) is a vector: it includes both magnitude and direction. Acceleration (a) is the rate of change of velocity, measured in metres per second squared (m s⁻²).
运动学在不考虑运动原因的情况下描述运动。位移(s)是矢量量,单位为米(m),表示相对于固定原点的位置变化。速率是标量,而速度(v)是矢量:同时包含大小和方向。加速度(a)是速度的变化率,单位为米每二次方秒(m s⁻²)。
In one-dimensional motion, choose a positive direction and remain consistent throughout. A negative acceleration means the object is accelerating in the opposite direction to your chosen positive direction — this is not necessarily the same as deceleration, which only means the speed is decreasing.
在一维运动中,选定正方向并在全过程中保持一致。负加速度意味着物体沿你所选正方向的相反方向加速——这未必等同于减速,减速仅表示速率在减小。
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Displacement is the straight-line distance from the start point, with direction.
位移是从起点到终点的直线距离,且带有方向。
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Average velocity = total displacement ÷ total time.
平均速度 = 总位移 ÷ 总时间。
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Instantaneous velocity is found from the gradient of a displacement-time graph.
瞬时速度可通过位移-时间图像的斜率求得。
2. SUVAT Equations for Constant Acceleration | 匀变速直线运动的SUVAT方程
When acceleration is constant, the five SUVAT equations relate displacement (s), initial velocity (u), final velocity (v), acceleration (a) and time (t). These equations are the backbone of nearly every AS Mechanics kinematics question.
当加速度恒定时,五个SUVAT方程将位移(s)、初速度(u)、末速度(v)、加速度(a)和时间(t)联系起来。这些方程是几乎所有AS力学运动学问题的核心基础。
v = u + at
s = ut + ½at²
v² = u² + 2as
s = ½(u + v)t
Each equation omits one variable, so choose the equation that uses the three quantities you know and the one you need. Always list what you know, draw a small diagram, and state your positive direction before substituting.
每个方程都省略一个变量,因此请根据已知的三个量和需求的一个量来选择合适的方程。始终先列出已知量,画出简图,并在代入前明确正方向。
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Use v = u + at when time is involved and acceleration is constant.
涉及时间且加速度恒定,使用 v = u + at。
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Use v² = u² + 2as when time is not given.
题目未给时间,使用 v² = u² + 2as。
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Check units: convert km h⁻¹ to m s⁻¹ by dividing by 3.6.
检查单位:将 km h⁻¹ 转换为 m s⁻¹,需除以 3.6。
3. Motion Graphs: s–t and v–t | 运动图像:s–t 与 v–t
Displacement-time graphs show position against time. The gradient at any point gives the velocity. A straight line means constant velocity, a horizontal line means stationary, and a curve means acceleration or deceleration.
位移-时间图像展示位置随时间的变化。任意点的斜率给出速度。直线表示匀速运动,水平线表示静止,曲线表示加速或减速。
Velocity-time graphs carry even more information. The gradient gives acceleration, and the area under the graph between two times gives the displacement during that interval. When the velocity crosses the time axis, the object has changed direction.
速度-时间图像包含更多信息。斜率给出加速度,图像与时间轴围成的面积给出该时间段内的位移。当速度线穿过时间轴时,表示物体改变了运动方向。
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Velocity-time graph: gradient = acceleration, area = displacement.
速度-时间图像:斜率 = 加速度,面积 = 位移。
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Acceleration-time graph: area = change in velocity.
加速度-时间图像:面积 = 速度变化量。
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On a v–t graph, a straight horizontal line means zero acceleration (constant velocity).
在 v–t 图像上,水平直线表示零加速度(匀速运动)。
For a v–t graph, the area under trapezium-shaped regions is commonly needed. Use the trapezium rule: area = ½(a + b)h, or split the shape into rectangles and triangles.
对于 v–t 图像,常需要计算梯形区域的面积。使用梯形公式:面积 = ½(a + b)h,或将图形拆分为矩形和三角形。
4. Vertical Motion Under Gravity | 重力作用下的竖直运动
Near the Earth’s surface, all freely falling objects experience constant acceleration due to gravity, g ≈ 9.8 m s⁻², directed downwards. For AQA and OxfordAQA papers you may use g = 9.8 m s⁻² unless told otherwise.
在地球表面附近,所有自由落体均受到恒定的重力加速度,g ≈ 9.8 m s⁻²,方向竖直向下。AQA与牛津AQA考试中,如无特殊说明,取 g = 9.8 m s⁻²。
When an object is thrown upwards, it decelerates at 9.8 m s⁻² until its velocity reaches zero at the highest point, then it accelerates back downwards. Crucially, the time to reach max height equals the time to fall back to the launch point, and the return speed equals the launch speed (neglecting air resistance).
物体竖直上抛时,以 9.8 m s⁻² 的加速度减速,直到最高点速度为零,然后向下加速。关键在于:到达最高点的时间等于落回抛出点的时间,且落回速度等于抛出速度(忽略空气阻力)。
Worked example: A ball is thrown vertically upwards at 15 m s⁻¹. Find the maximum height reached. Take upwards as positive. At the top, v = 0, u = 15 m s⁻¹, a = −9.8 m s⁻². Using v² = u² + 2as: 0 = 15² + 2(−9.8)s, so s = 225 ÷ 19.6 ≈ 11.5 m.
例题:小球以 15 m s⁻¹ 竖直上抛,求最大上升高度。取向上为正,最高点处 v = 0,u = 15 m s⁻¹,a = −9.8 m s⁻²。由 v² = u² + 2as:0 = 15² + 2(−9.8)s,故 s = 225 ÷ 19.6 ≈ 11.5 m。
5. Forces: Resultants and Force Diagrams | 力:合力与受力分析图
A force is a vector quantity measured in newtons (N). In Mechanics, common forces include weight (W = mg), normal reaction (R or N), tension (T), thrust, friction (F) and applied forces. Always draw a clear force diagram showing all forces acting on the particle.
力是矢量量,单位为牛顿(N)。力学中常见的力包括重力(W = mg)、法向反作用力(R 或 N)、张力(T)、推力、摩擦力(F)和外加力。务必画出清晰的受力分析图,标明作用在质点上的所有力。
To find the resultant force, resolve all forces into perpendicular components. In many AS questions, you resolve parallel and perpendicular to the plane or the direction of motion. Use F = ma in component form:
求合力时,将所有力分解为互相垂直的分量。在多数AS题目中,沿斜面方向或运动方向以及垂直于该方向进行分解。利用分量形式的 F = ma:
Fₙₑₜ = ma
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Resolve horizontally and vertically on a horizontal plane.
在水平面上分别沿水平和竖直方向分解。
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Weight always acts vertically downwards through the centre of mass.
重力始终竖直向下,作用线通过质心。
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Normal reaction acts perpendicular to the surface, pushing away from it.
法向反作用力垂直于接触面,指向远离接触面的方向。
6. Newton’s Laws of Motion | 牛顿运动定律
Newton’s First Law states that a body remains at rest or moves with constant velocity unless acted on by a resultant external force. This is why a car cruising at steady speed has zero resultant force — the driving force exactly balances resistance.
牛顿第一定律指出:物体在不受合外力作用时,保持静止状态或匀速直线运动状态。这正是汽车匀速行驶时合力为零的原因——驱动力恰好与阻力平衡。
Newton’s Second Law states that the resultant force on an object equals the product of its mass and acceleration: F = ma. This links dynamics (forces) with kinematics (acceleration). If the resultant force is zero, acceleration is zero.
牛顿第二定律指出:物体所受合外力等于其质量与加速度的乘积:F = ma。这连接了动力学(力)与运动学(加速度)。若合外力为零,则加速度为零。
Newton’s Third Law states that every action has an equal and opposite reaction. The forces are equal in magnitude, opposite in direction, and act on different bodies. A book pressing down on a table and the table pushing up on the book are a Newton III pair.
牛顿第三定律指出:每一个作用力都有大小相等、方向相反的反作用力。两个力大小相等、方向相反,且作用于不同物体。书向下压桌子和桌子向上推书就是一对牛顿第三定律作用力与反作用力。
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F = ma applies to the net resultant force, not individual forces.
F = ma 中的 F 是合外力,而非某个单独的力。
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On inclined planes, resolve weight into components mg sin θ (down the slope) and mg cos θ (perpendicular to the slope).
在斜面上,将重力分解为 mg sin θ(沿斜面向下)和 mg cos θ(垂直斜面)。
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Newton III pairs always act on two different objects.
牛顿第三定律的力对总是作用于两个不同的物体上。
7. Connected Particles and Pulleys | 连接体与滑轮
Connected particles move with the same acceleration when connected by an inextensible string over a smooth pulley. Treat the whole system as one body to find acceleration, then consider individual bodies to find internal tensions.
通过不可伸长轻绳跨过光滑滑轮连接的物体具有相同的加速度。将整个系统视为一个整体求加速度,再分别研究单个物体求绳子的内部张力。
For two masses m₁ and m₂ hanging over a pulley, with m₁ > m₂, the system accelerates with magnitude:
对于滑轮两侧悬挂质量 m₁ 和 m₂ 的物体,若 m₁ > m₂,系统加速度大小为:
a = (m₁ − m₂)g ÷ (m₁ + m₂)
Tension is found by applying F = ma to one mass alone. For the heavier mass m₁: m₁g − T = m₁a. Substitute the value of a to find T. Remember that tension is not equal to either weight — it lies between the two weights.
张力通过对单个质量应用 F = ma 求得。对较重质量 m₁:m₁g − T = m₁a。代入 a 的值即可求出 T。注意张力不等于任一物体的重量——它介于两个重量之间。
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For connected particles on a smooth horizontal table, T = ma for the table mass and m₁g − T = m₁a for the hanging mass.
对于水平光滑桌面上的连接体,桌面上的质量满足 T = ma,悬挂质量满足 m₁g − T = m₁a。
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Inextensible string implies both particles have equal acceleration magnitude.
不可伸长轻绳意味着两个质点的加速度大小相等。
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A smooth pulley changes the direction of tension but not its magnitude.
光滑滑轮改变张力的方向,但不改变张力的大小。
8. Friction and the Coefficient of Friction | 摩擦力与摩擦系数
Friction is a contact force that opposes relative motion or attempted motion between two surfaces. Its maximum value is proportional to the normal reaction R, with the constant of proportionality called the coefficient of friction, μ (mu). The limiting friction is given by:
摩擦力是阻止两个接触面之间相对运动或相对运动趋势的接触力。其最大值与法向反作用力 R 成正比,比例常数称为摩擦系数 μ(mu)。极限摩擦力为:
Fₘₐₓ = μR
If the applied force is less than μR, friction adjusts to exactly balance the applied force and the object stays at rest. Once the applied force exceeds μR, the object begins to slide and friction stays at its limiting value μR.
若施加的力小于 μR,摩擦力会调整到恰好平衡施加的力,物体保持静止。一旦施加的力超过 μR,物体开始滑动,摩擦力保持在极限值 μR。
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On an inclined plane at angle θ, the maximum angle of repose satisfies tan θ = μ.
在倾角为 θ 的斜面上,最大静止角满足 tan θ = μ。
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μ is dimensionless and typically between 0 and 1 for most surfaces.
μ 无量纲,对大多数接触面通常介于 0 与 1 之间。
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Always compute R from perpendicular equilibrium before using F = μR.
使用 F = μR 之前,务必先从垂直方向的平衡条件求出 R。
9. Momentum and Impulse | 动量与冲量
Linear momentum is defined as the product of mass and velocity: p = mv, measured in kg m s⁻¹. Momentum is a vector quantity. The principle of conservation of momentum states that in a closed system with no external forces, total momentum before a collision equals total momentum after.
线动量定义为质量与速度的乘积:p = mv,单位为 kg m s⁻¹。动量是矢量。动量守恒定律指出:在没有外力的封闭系统中,碰撞前总动量等于碰撞后总动量。
m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂
Impulse is the change in momentum, equal to force multiplied by time: Ft = mv − mu. The unit of impulse is N s, which is equivalent to kg m s⁻¹. On a force-time graph, the area under the graph represents the impulse.
冲量是动量的变化量,等于力乘以时间:Ft = mv − mu。冲量的单位是 N s,与 kg m s⁻¹ 等价。在力-时间图像上,曲线下的面积表示冲量。
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In a perfectly inelastic collision, the objects stick together and move with a common final velocity.
在完全非弹性碰撞中,物体粘在一起,以共同速度运动。
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In an elastic collision, both momentum and kinetic energy are conserved.
在弹性碰撞中,动量和动能均守恒。
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For a bouncing ball, impulse equals m(v_after − v_before) with careful sign handling.
对于弹跳的球,冲量等于 m(v_后 − v_前),需特别注意正负号处理。
10. Work, Energy and Power | 功、能与功率
Work is done when a force moves an object through a displacement: W = Fs, measured in joules (J). When the force is at an angle θ to the displacement, use W = Fs cos θ. No work is done when the force is perpendicular to the displacement, such as the normal reaction on a horizontal surface.
当力使物体产生位移时做功:W = Fs,单位为焦耳(J)。当力与位移方向成 θ 角时,使用 W = Fs cos θ。当力垂直于位移方向时,不做功,例如水平面上法向反作用力不做功。
Kinetic energy is the energy of motion: KE = ½mv². Gravitational potential energy is the energy stored due to height: PE = mgh. The work-energy principle states that the net work done on an object equals its change in kinetic energy.
动能是物体由于运动而具有的能量:KE = ½mv²。重力势能是由于高度而储存的能量:PE = mgh。功能原理指出:对物体做的净功等于其动能的变化量。
Power is the rate of doing work: P = W/t, or equivalently P = Fv for constant force and velocity. Power is measured in watts (W), where 1 W = 1 J s⁻¹.
功率是做功的速率:P = W/t,在恒力恒速下等价于 P = Fv。功率的单位是瓦特(W),1 W = 1 J s⁻¹。
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Work done against gravity when climbing a height h is mgh, independent of the path.
攀爬高度 h 时克服重力做功为 mgh,与路径无关。
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On a slope of angle θ, the gravitational force down the slope is mg sin θ.
在倾角为 θ 的斜面上,沿斜面向下的重力分量为 mg sin θ。
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For a vehicle at constant speed, engine power P = driving force × speed.
对匀速行驶的车辆,发动机功率 P = 驱动力 × 速度。
11. Exam-Style Practice Questions | 考试风格练习题
Apply your knowledge to these questions drawn directly from the AQA/9660 Mechanics specification. Attempt each one fully before checking the worked solution.
将你的知识应用到以下直接源自AQA/9660力学考纲的题目中。请先完整作答,再对照解题过程。
Question 1 | 题1: A car accelerates uniformly from rest to 24 m s⁻¹ in 12 s. Calculate the acceleration and the distance travelled in this time.
题1:汽车从静止开始匀加速,在12秒内达到 24 m s⁻¹。求加速度和这段时间内行驶的距离。
Solution: a = (v − u)/t = 24/12 = 2 m s⁻². Distance s = ½(u + v)t = ½ × 24 × 12 = 144 m.
解答:a = (v − u)/t = 24/12 = 2 m s⁻²。距离 s = ½(u + v)t = ½ × 24 × 12 = 144 m。
Question 2 | 题2: A mass of 5 kg is pulled along a rough horizontal surface by a horizontal force of 20 N. The coefficient of friction is 0.3. Find the acceleration.
题2:质量为 5 kg 的物体在粗糙水平面上受到 20 N 的水平拉力。摩擦系数为 0.3。求加速度。
Solution: R = mg = 5 × 9.8 = 49 N. Friction F = μR = 0.3 × 49 = 14.7 N. Resultant force = 20 − 14.7 = 5.3 N. a = 5.3/5 = 1.06 m s⁻².
解答:R = mg = 5 × 9.8 = 49 N。摩擦力 F = μR = 0.3 × 49 = 14.7 N。合力 = 20 − 14.7 = 5.3 N。a = 5.3/5 = 1.06 m s⁻²。
Question 3 | 题3: A 2 kg ball moving at 4 m s⁻¹ collides head-on with a stationary 3 kg ball. After collision they move together. Find the common velocity and the kinetic energy lost.
题3:质量为 2 kg 的小球以 4 m s⁻¹ 与静止的 3 kg 小球发生正碰。碰撞后两球一起运动。求共同速度及损失的动能。
Solution: Momentum: 2 × 4 = (2 + 3)v → v = 8/5 = 1.6 m s⁻¹. Initial KE = ½ × 2 × 4² = 16 J. Final KE = ½ × 5 × 1.6² = 6.4 J. Energy lost = 16 − 6.4 = 9.6 J.
解答:动量:2 × 4 = (2 + 3)v → v = 8/5 = 1.6 m s⁻¹。初始动能 = ½ × 2 × 4² = 16 J。末动能 = ½ × 5 × 1.6² = 6.4 J。损失能量 = 16 − 6.4 = 9.6 J。
Question 4 | 题4: A particle is projected vertically upwards with speed 20 m s⁻¹. What is the maximum height reached and the total time of flight?
题4:质点以 20 m s⁻¹ 竖直上抛。求最大高度和总飞行时间。
Solution: v² = u² + 2as → 0 = 400 − 19.6s → s = 20.4 m. Time to top: v = u + at → 0 = 20 − 9.8t → t = 2.04 s. Total flight time = 4.08 s.
解答:v² = u² + 2as → 0 = 400 − 19.6s → s = 20.4 m。到达最高点时间:v = u + at → 0 = 20 − 9.8t → t = 2.04 s。总飞行时间 = 4.08 s。
12. Common Mistakes and Examiner Tips | 常见错误与考官提示
Examiners consistently report the same errors in Mechanics papers. Knowing these pitfalls can save you crucial marks in your topic test and final examination.
考官反复指出力学试卷中出现同样的错误。了解这些陷阱能在你的主题测试和最终考试中帮你挽回关键分数。
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Mistake 1: Applying SUVAT equations to motion with non-constant acceleration. These equations only work when a is constant. | 错误1:对非恒定加速度的运动套用SUVAT方程。这些方程仅在 a 恒定时成立。
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Mistake 2: Forgetting to convert units, especially km h⁻¹ to m s⁻¹. | 错误2:忘记换算单位,尤其是 km h⁻¹ 到 m s⁻¹。
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Mistake 3: Incorrect sign convention for vertical motion — decide up or down as positive and stick to it. | 错误3:竖直运动中正负号规则错误——选定向上或向下为正并保持一致。
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Mistake 4: Confusing mass and weight. Weight is a force: W = mg. | 错误4:混淆质量与重力。重力是力:W = mg。
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Mistake 5: Drawing force diagrams with missing forces, such as normal reaction or friction. | 错误5:受力分析图遗漏力,如漏掉法向反作用力或摩擦力。
Always show your working clearly and state the equation you use before substituting numbers. Scheme marks are awarded for each step. In a topic test, allocate about 5 minutes per mark, and for multi-part questions, use the answer from part (a) in part (b) — marking is usually consecutive, so a small error early costs little if the method remains correct.
始终清晰地展示你的解题过程,并在代入数字之前写明所用的方程。评分标准按步骤给分。在主题测试中,每分钟约对应1分值的思考量;对于多小问的题目,将第(a)问的结果用于第(b)问——评分通常具有连贯性,只要方法正确,早期的小错误不会导致大量扣分。
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