A student is attempting to determine ggg, the acceleration due to gravity, using two different experimental setups.
Method A: Vertical Drop A small brass ball is dropped from rest from a height of 1.50 m1.50\text{ m}1.50 m. The student measures the time taken to fall to the floor using a manual digital stopwatch.
Method B: Inclined Track A low-friction trolley is released from rest from the top of a ramp of length 2.200 m2.200\text{ m}2.200 m, inclined at an angle of 20.0∘20.0^\circ20.0∘ to the horizontal. The researcher measures the time taken to reach the bottom of the ramp using the same manual digital stopwatch.
Single measurements from these setups are recorded below:
| Method | Distance / m\text{m}m | Angle / ∘^\circ∘ | Time / s\text{s}s |
|---|---|---|---|
| Method A (Vertical Drop) | 1.501.501.50 | −-− | 0.550.550.55 |
| Method B (Inclined Track) | 2.2002.2002.200 | 20.020.020.0 | 1.151.151.15 |
Compare and discuss the uncertainties associated with the values of ggg calculated from these single sets of measurements.
Describe how the student should analyze a full range of data for both methods (by varying the independent variables) to obtain more reliable values for ggg and estimate their uncertainties.
2 exam-style questions on OCR A A Level Physics Practical skills assessed in a written examination, covering Planning, Implementing, Analysis, and Evaluation. Each one has a worked solution and a mark scheme showing where the marks go.