A learner driver uses a computer reaction timer. The screen changes after a random delay and the learner clicks as soon as the screen changes.
The learner repeats the test five times.
| Test | Reaction time in s\text{s}s |
|---|---|
| 1 | 0.32 |
| 2 | 0.31 |
| 3 | 0.80 |
| 4 | 0.30 |
| 5 | 0.31 |
Give the anomalous reaction time.
The anomalous result is not used.
Calculate the mean reaction time for the other four results.
Give one reason why calculating a mean from repeated readings gives a more reliable result than using one reading.
The learner later drives a campervan at a constant speed of 15 m/s. The instructor uses the mean from (b) as an estimate of the learner's reaction time while driving.
Use the equation
d=vtd=vtd=vt
to calculate an estimate for the thinking distance.
126 exam-style questions on Edexcel GCSE Physics 2.5 Stopping and braking distances, covering 2.5.1 Stopping distance and reaction time, 2.5.2 Factors affecting stopping distance, 2.5.3 Dangers of large decelerations, and 2.5.4 Braking distance and initial speed. Each one has a worked solution and a mark scheme showing where the marks go.