📚 AS Physics Unit 1 Mark Scheme (June 2022): Mastering Experimental Investigations | AS物理单元1 2022年6月评分方案：掌握实验探究
The AS Physics Unit 1 exam requires not only theoretical knowledge but also a deep understanding of practical investigations. The June 2022 mark scheme reveals exactly what examiners look for when assessing your experimental skills. By studying these marking guidelines, you can learn how to structure answers, handle data, and evaluate uncertainties to achieve top marks.
AS物理单元1考试不仅要求理论知识，还要求对实验探究有深刻的理解。2022年6月的评分方案揭示了考官在评估实验技能时的具体标准。通过学习这些评分指南，你可以学会如何构建答案、处理数据和评估不确定度，从而取得高分。
1. Experimental Design and Variables | 实验设计与变量
Every experimental investigation in AS Physics must begin with a clear identification of the independent, dependent, and control variables. For example, in a mass-spring system investigating the period T, the mass m is the independent variable, T is the dependent variable, and the spring constant k must be controlled by using the same spring throughout. The June 2022 mark scheme usually awards marks for explicitly stating how control variables are kept constant and why this matters.
AS物理中的每一项实验探究都必须从清楚识别自变量、因变量和控制变量开始。例如，在研究弹簧质量系统周期T的实验中，质量m是自变量，T是因变量，而弹簧常数k必须通过始终使用同一根弹簧来控制。2022年6月的评分方案通常会对明确说明如何保持控制变量不变及其原因给予分数。
When you answer an experimental design question, describe the apparatus and the range of values you will use. For instance, measure the time for 10 complete oscillations and repeat each mass reading three times to reduce random errors. The mark scheme expects you to explain that timing multiple oscillations reduces the effect of human reaction time on the measured period.
当你回答实验设计题时，要描述仪器以及你将使用的数值范围。例如，测量10次完整振荡的时间，并对每个质量读数重复三次以减少随机误差。评分方案期望你解释计时多个周期可以减少人体反应时间对测量周期的影响。
2. Obtaining Accurate Data | 获取准确数据
Accuracy starts with careful measurement techniques. Mark schemes regularly reward the use of appropriate instruments: a digital stopwatch for timing intervals, a metre rule for lengths, and a set square to ensure alignment. For a mass-spring experiment, you should also measure the mass with a digital balance or use known slotted masses. The June 2022 scheme would penalise measurements that lack precision, such as recording the period to only one decimal place when the stopwatch reads to 0.01 s.
精确度始于细致的测量技术。评分方案通常会奖励使用适当的仪器：用数字秒表计时间隔，用米尺测量长度，并用三角尺确保对齐。对于弹簧质量实验，你还需要用电子天平测量质量或使用已知的开槽质量块。2022年6月的方案会扣分由于测量精度不足，例如虽然秒表可读数到0.01秒，却只把周期记录到一位小数。
Repeating measurements and calculating a mean is essential. The mark scheme expects you to present repeated readings in a table and discard any anomalous results after careful judgement. You should also explain that taking repeat readings reduces the impact of random errors and allows for the calculation of uncertainty from the spread of values.
重复测量并计算平均值至关重要。评分方案期望你将重复读数记录在表格中，并在仔细判断后舍弃任何异常结果。你还应说明，进行重复测量可以减少随机误差的影响，并允许根据数值分布范围计算不确定度。
3. Presenting Data in Tables | 在表格中呈现数据
Data tables must be clear, logical, and complete. Each column heading should include both the quantity and its unit, separated by a slash, e.g., ‘Mass m / kg’ or ‘Time for 10T / s’. The June 2022 mark scheme typically awards a mark for good table layout with units in headings, consistent significant figures in recorded data, and the inclusion of mean values. Avoid putting units inside the data cells, as this can cost a mark.
数据表格必须清晰、逻辑性强且完整。每个列标题都应包含物理量及其单位，用斜线分隔，例如 “Mass m / kg” 或 “Time for 10T / s”。2022年6月的评分方案通常会对表格布局良好（标题带单位、记录数据有效数字一致且包含平均值）给予分数。避免把单位放在数据单元格内，因为这可能导致失分。
Here is an example of a well-designed table:
以下是一个设计良好的表格示例：
| Mass m / kg | Time for 10T t₁ / s | Time for 10T t₂ / s | Time for 10T t₃ / s | Mean time for 10T / s |
|---|---|---|---|---|
| 0.100 | 6.12 | 6.10 | 6.17 | 6.13 |
Notice the consistent use of three significant figures and the separate column for the mean. The mark scheme would accept this as a clear record of raw data.
请注意，有效数字位数一致且平均值独立成列。评分方案会认可这是一个清晰的原始数据记录。
4. Graphical Analysis and Best-Fit Lines | 图形分析和最佳拟合线
Plotting a graph is a core skill in Unit 1 practical assessment. The June 2022 mark scheme emphasises that data points must be plotted as small, neat crosses or circles, and the axes must be labelled with the quantity and unit. The scale should be chosen so that the plotted points occupy more than half the graph grid in each direction. A best-fit straight line should be drawn – not a dot-to-dot line – with a balance of points on either side.
绘制图形是单元1实践评估的核心技能。2022年6月的评分方案强调，数据点必须以细小整洁的叉号或圆圈绘制，坐标轴必须标有物理量和单位。刻度应选择使得描点在各方向上占据图形网格的一半以上。应当画出最佳拟合直线——而不是逐点连线——并使点均匀分布在直线两侧。
When the relationship is linear, as with T² against m, the mark scheme expects you to draw a line of best fit that passes through as many error bars as possible (if error bars are included). If the graph is curved, you may need to process the data first – for example, plotting T² versus m to linearise the relationship. Marks are allocated for correct choice of variables to achieve a straight line.
当关系为线性时，例如 T² 与 m 的关系图，评分方案期望你画出尽可能穿过更多误差棒的最佳拟合线（如果包含误差棒）。如果图形是曲线，你可能需要先处理数据——例如，绘制T²与m的关系图以使关系线性化。正确选择变量以获得直线也会获得分数。
5. Calculating Quantities from Graphs | 从图像计算物理量
The gradient and intercept of a straight-line graph often give the desired physical quantity. In the mass-spring investigation, the accepted equation T = 2π√(m/k) can be squared to give T² = (4π²/k) m. Thus, a graph of T² on the y-axis against m on the x-axis should yield a straight line through the origin with gradient = 4π²/k. The June 2022 mark scheme requires you to show clearly on the graph the triangle used to calculate gradient, using points that are far apart and not actual data points.
直线图的斜率和截距常常给出想要的物理量。在弹簧质量探究中，公认方程 T = 2π√(m/k) 可以平方得到 T² = (4π²/k) m。因此，以T²为y轴，以m为x轴作图，应得到一条通过原点的直线，斜率为 4π²/k。2022年6月的评分方案要求你在图上清楚地标出用于计算斜率的三角形，使用间距较远且非实际数据点的坐标点。
k = 4π² / gradient
Once the gradient is determined, substitute it carefully with its unit. If the gradient is found to be 3.95 s² kg⁻¹, then k = 4π² / 3.95 ≈ 10.0 kg s⁻². Marks are given for both correct calculation and correct unit handling.
一旦确定了斜率，需小心代入并带上单位。若得出斜率为 3.95 s² kg⁻¹，则 k = 4π² / 3.95 ≈ 10.0 kg s⁻²。正确计算和单位处理都能获得分数。
6. Dealing with Uncertainties | 处理不确定度
Every measurement carries uncertainty, and the mark scheme expects you to identify sources and quantify their effects. For the period, the absolute uncertainty might be half the smallest division of the stopwatch (0.01 s) or the spread of repeat readings, whichever is larger. For mass, uncertainty comes from the balance resolution or the tolerance of slotted masses. The June 2022 scheme often awards marks for stating both absolute and percentage uncertainties.
每个测量都带有不确定度，评分方案期望你确定来源并量化其影响。对于周期，绝对不确定度可能是秒表最小分度值的一半（0.01 s）或重复读数的偏差范围，取较大者。对于质量，不确定度来自天平分辨率或开槽质量块的公差。2022年6月的方案通常会对列出绝对和百分比不确定度给予分数。
| Quantity | Uncertainty type | Typical source |
|---|---|---|
| Time | Random | Reaction time, stopwatch precision |
| Mass | Systematic/random | Uncalibrated balance, parallax |
Percentage uncertainty is calculated by (absolute uncertainty / mean value) × 100%. When combining uncertainties, the mark scheme may require you to propagate, for example using the worst-acceptable-line method for the gradient instead of algebraic propagation rules.
百分比不确定度由 (绝对不确定度 / 平均值) × 100% 计算。在合成不确定度时，评分方案可能要求你通过传递方法，例如使用最差接受线法求斜率不确定度，而非代数合成规则。
7. The Worst-Acceptable-Line Method | 最差接受线方法
The worst-acceptable-line (or worst fit) technique is a straightforward way to estimate the uncertainty in a gradient. From the plotted data points and their error bars, you draw a steepest possible line that still reasonably fits the data (the ‘worst’ line in terms of gradient) and a shallowest one. The difference between the best gradient and the worst gradient gives the absolute uncertainty in the gradient. The June 2022 mark scheme expects you to show these lines on the graph and label them clearly.
最差接受线（或最差拟合）技术是估计斜率不确定度的直接方法。根据已描的点和误差棒，画出仍能合理拟合数据的最陡线（梯度角度上的“最差”线）和最浅线。最佳斜率与最差斜率之间的差值即为斜率的绝对不确定度。2022年6月的评分方案期望你在图上画出这些线并清晰标注。
Uncertainty in gradient = |steepest gradient − shallowest gradient| / 2
From this, the uncertainty in k can be derived. If the best gradient is 3.95 s² kg⁻¹ and the worst gradient range gives ±0.15 s² kg⁻¹, then the uncertainty in k is found by considering the maximum and minimum possible values of k. The mark scheme will look for a clear final value with an associated absolute uncertainty, e.g., k = 10.0 ± 0.4 kg s⁻².
由此可得出k的不确定度。若最佳斜率为 3.95 s² kg⁻¹，最差斜率范围给出 ±0.15 s² kg⁻¹，则k的不确定度通过考虑k可能的最大值和最小值得到。评分方案将寻找明确的最终值及相关的绝对不确定度，例如 k = 10.0 ± 0.4 kg s⁻²。
8. Evaluating the Experiment and Suggesting Improvements | 评估实验并提出改进
A top-scoring evaluation identifies not just the sources of error but also their impact on the result and realistic improvements. In the mass-spring experiment, a systematic error could arise if the spring is permanently stretched beyond its elastic limit, making the equation invalid. A random error arises from timing inaccuracies. The June 2022 mark scheme specifically rewards suggestions that are practical, such as using a fiducial marker to improve timing precision or a light gate to eliminate reaction time.
一份高分的评估不仅要确定误差来源，还要阐述它们对结果的影响以及切实可行的改进措施。在弹簧质量实验中，如果弹簧被永久拉伸超出弹性极限，系统误差就会产生，使方程失效。随机误差来自计时不准确。2022年6月的评分方案特别奖励实用性的建议，比如使用基准标记以提高计时精度，或者采用光电门来消除反应时间。
When you write your evaluation, link each identified error to a specific improvement. For example, if you notice that the spring oscillates out of alignment, a suggestion to use a guide rod or ensure small amplitude could gain credit. Always justify why the improvement will reduce the error.
当你撰写评估时，要把每个确定的误差与具体改进措施联系起来。例如，如果你注意到弹簧偏离方向振荡，那么建议使用导向杆或确保小振幅就能得分。始终要论证为什么该改进会减少误差。
9. Common Mistakes and How to Avoid Them | 常见错误及避免方法
Many students lose marks in Unit 1 experiments by overlooking details that the June 2022 mark scheme penalises. Common pitfalls include: forgetting to label axes with units, using an inappropriate scale that produces a tiny graph, drawing a dot-to-dot line instead of a best-fit line, calculating the gradient from two adjacent data points rather than widely spaced points, and omitting the direction of any difference when discussing percentage difference from an accepted value.
许多学生在单元1实验中因忽视细节而失分，这正是2022年6月评分方案所惩罚的。常见的陷阱包括：忘记给坐标轴标注单位，使用不恰当的刻度使图形很小，画逐点连线而非最佳拟合线，从两个相邻数据点而不是间距很远的点计算斜率，以及在讨论与标准值的百分比差异时遗漏差值的符号方向。
Also, many students mix up precision and accuracy. The mark scheme expects you to state that repeating readings improves precision (reduces random error) but does not affect systematic error. Ensure you never claim that repeating an experiment eliminates all errors – it only reduces random scatter. Furthermore, always check your units throughout the calculation; a unit error in the final answer can cost a mark.
此外，许多学生混淆了精确度和准确度。评分方案期望你说明重复测量可提高精确度（减少随机误差），但不影响系统误差。确保你不会声称重复实验可以消除所有误差——它只能减少随机离散。此外，要始终检查计算中的单位；最终答案中的单位错误可能导致丢分。
10. Applying the Mark Scheme to a Sample Question | 将评分方案应用于样题
Consider this typical AS Unit 1 question based on the June 2022 style: ‘A student investigates a mass-spring system. She records the time for 10 oscillations for six different masses and plots T² against m. Her graph has a slope of 4.10 s² kg⁻¹. Identify one precaution taken to improve accuracy and calculate the value of k.’ The mark scheme would award one mark for stating that the student used small amplitudes to remain within Hooke’s law, and two marks for k = 4π² / 4.10 = 9.6 kg s⁻², with the correct unit.
思考以下这个基于2022年6月风格的典型AS单元1问题：“一名学生研究一个弹簧质量系统。她记录了六个不同质量下10次振荡的时间，并绘制了T²与m关系图。她得到的图线斜率为4.10 s² kg⁻¹。指出她采取的一项提高精确度的预防措施，并计算k值。”评分方案会给出一分用于说明该学生使用了小振幅以遵守胡克定律，两分用于 k = 4π² / 4.10 = 9.6 kg s⁻² 并带正确单位。
Another sample evaluation prompt might ask you to describe how to determine the uncertainty in k. A full-mark answer would describe plotting the worst-acceptable line, calculating the alternative gradient, finding the range of k, and stating the final answer as k = 9.6 ± 0.3 kg s⁻². Always show your working on the graph and in your written solution, as the mark scheme allocates marks to each step.
另一道样题评估提示可能会要求你描述如何确定k的不确定度。满分答案应描述绘制最差接受线、计算另一个斜率、求出k的范围，并给出最终答案 k = 9.6 ± 0.3 kg s⁻²。始终在图上和书面解答中呈现你的步骤，因为评分方案对每一步都分配了分数。
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