Measuring motion without hiding uncertainty
Speed and acceleration are calculated from measured lengths and times. Timing uncertainty can dominate a short interval even when the distance is measured carefully.
Follow the reasoning
- Identify the length and time actually measured by the apparatus.
- Combine their uncertainties for the calculated speed.
- Use a suitable graph and large gradient triangle when finding acceleration.
Try it in a past paper 4
Open the question, then use its mark scheme to check your work.
Question 24(b)–(e)
Analyse falling motion, improve timing and sketch a bounce.
Question 3
Measure a falling ball’s height and time, then determine g and its uncertainty from a graph.
Question 25
Use video timing and displacement data to determine terminal speed in water.
Question 3
Describe electronic timing and determine g from a squared-time graph.
A curated collection checked against the question papers and mark schemes; not a complete past-paper catalogue. Links open official OCR PDFs in a new tab.
Put the ideas to work
More practice is on its way
No PhysicsUK question linked yet. New eligible questions appear here as the bank grows.
Specification outcomes (6)
- 3.1.1(a) Define and use displacement, instantaneous speed, average speed, velocity and acceleration.
- 3.1.1(c) Use displacement–time graphs to determine velocity as the gradient.
- 3.1.1(d) Use velocity–time graphs to determine acceleration as the gradient and displacement as the area under the graph, including estimation for non-linear graphs.
- 2.2.1(a) Understand systematic errors (including zero errors) and random errors in measurements.
- 2.2.1(c) Calculate absolute and percentage uncertainties when data are combined by addition, subtraction, multiplication, division or raising to powers.
- 2.2.1(d) Use graphical treatment of errors and uncertainties, including line of best fit, worst line, absolute and percentage uncertainties, and percentage difference.