Required practical 7: reaction time and fair comparison
הוצג| English | משמעות |
|---|---|
| anticipation/ænˈtɪsɪpeɪʃn/ | התקוויות |
| reaction time/rɪˈækʃn taɪm/ | זמן תגובה |
What would explain this observation?
- A ruler-drop result can improve because someone learns when to expect the drop. A fair investigation must distinguish the chosen factor from practice and anticipation 预期.
Build the model
- Reaction time 反应时间 is the interval between a stimulus and a response.
- In required practical 7 a suitable factor is investigated under school supervision.
- A ruler-drop method measures the distance fallen before a catch.
- Use a supplied conversion chart if time is required; distance in centimetres is not automatically time in seconds.
- reaction time: The interval from a stimulus to the response.
- anticipation: Responding based on an expected cue before the actual stimulus.
Why should the releaser avoid giving a countdown?
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
A countdown lets the catcher anticipate the release, so the result measures prediction, not reaction to the actual event. Reaction time needs the stimulus to arrive without warning.
Match each technical term to its precise meaning.
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- The chosen factor must change while other relevant conditions stay comparable.
- Keep the starting ruler position, hand position, catching method and instructions consistent.
- Avoid advance cues to the release.
- Repeated trials reduce the influence of random variation; a planned order can reduce practice or fatigue effects.
- A shorter drop distance generally indicates a quicker catch in the same method.
In the lab: Use informed, voluntary participation and an alternative supplied-data task. Choose a low-risk factor such as a stated distraction under teacher guidance, not sleep deprivation, stimulants, illness, distress or strenuous exertion. Repeat enough trials, record all results and use a mean or justified treatment of an anomalous result. Do not rank students’ ability or infer medical conditions.
Which two habits make the investigation or model in this case more defensible?
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
Stating the conditions and assumptions lets others repeat the work exactly, and recording the supporting evidence lets them check the conclusion. Hiding disagreeing results removes the evidence that could challenge a wrong conclusion, and one measurement can never establish a wider claim.
Work from known quantities
- Known: model catch distances are 18, 22, 20, 19 and 21 cm.
- Mean = 100/5 = 20 cm.
- A second condition averaging 25 cm suggests slower catching under the same method.
- Without repeats, order control and comparable starting positions, the difference cannot confidently be assigned to the chosen factor.
Your turn: Model catch distances are 16, 20, 18 and 22 cm. Calculate the mean.
Model catch distances are 16, 20, 18 and 22 cm. Calculate the mean.
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
The result is 19 cm. Known: catch distances 16, 20, 18 and 22 cm. Use mean = sum / count. Sum = 16 + 20 + 18 + 22 = 76. Mean = 76/4 = 19 cm. No value may be silently discarded to improve the mean.
Check the conclusion and its limits
- A result is a measurement under particular conditions, not a permanent personal characteristic.
- Never silently discard the largest value just to improve the mean.
- A distance-to-time conversion must use the specified model or table rather than relabelling centimetres as milliseconds.
Not true: A ruler distance in centimetres is numerically the same as reaction time in seconds. Distance fallen is converted to reaction time through a stated model or table - it depends on gravitational acceleration. The number of centimetres is never numerically equal to the number of seconds.
- Reaction time is the interval between a stimulus and a response.
- The chosen factor must change while other relevant conditions stay comparable.
- Watch for: A result is a measurement under particular conditions, not a permanent personal characteristic.
Distance fallen is converted to reaction time through a stated model or table - it depends on gravitational acceleration.
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
True. Distance fallen is converted to reaction time through a stated model or table - it depends on gravitational acceleration. The number of centimetres is never numerically equal to the number of seconds.
The interval from a stimulus to the response: write the technical term.
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
reaction time means The interval from a stimulus to the response.