Question Constellation Sign up for free AQA · GCSE · Physics · Higher
Uncertainty from Repeated Acceleration Measurements
For one set of results, the force acting through the string was 2.0 N. The student released the trolley three times and determined the following values for acceleration: 1.36 m/s², 1.39 m/s² and 1.33 m/s².
Calculate the uncertainty in the values of acceleration.
Write your answer first. You can study the marking guidance whenever you need it.
Study the marking See what earns credit and compare it with a full-mark answer.
Marking points
- 1 Finds the range 0.06 m/s² or the mean 1.36 m/s².
- 2 Gives the half-range uncertainty as ±0.03 m/s².
Full-mark answer
Range = 1.39 − 1.33 = 0.06 m/s². Uncertainty = half the range = ±0.03 m/s².
Why this answer loses marks
Reports the full range as the uncertainty.
The spread is found first, but the uncertainty in the repeated results is half that range and needs the plus-minus form.