Question 19M.3.SL.TZ1.1b.ii
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.3.SL.TZ1.1b.ii |
| Level | SL | Paper | 3 | Time zone | TZ1 |
| Command term | Explain, State | Question number | b.ii | Adapted from | N/A |
In an experiment to measure the acceleration of free fall a student ties two different blocks of masses m1 and m2 to the ends of a string that passes over a frictionless pulley.
The student calculates the acceleration a of the blocks by measuring the time taken by the heavier mass to fall through a given distance. Their theory predicts that and this can be re-arranged to give .
In a particular experiment the student calculates that a = (0.204 ±0.002) ms–2 using m1 = (0.125 ±0.001) kg and m2 = (0.120 ±0.001) kg.
There is an advantage and a disadvantage in using two masses that are almost equal.
State and explain the disadvantage with reference to your answer to (a)(ii).
[2]
the percentage error in the difference of the masses is large ✔
leading to a large percentage error/uncertainty in g/of the experiment ✔
Do not accept ideas related to the mass/moment of inertia of the pulley.
In part ii) many were able to appreciate that the resultant percentage error in “g” was relatively large however linking this with what caused the large uncertainty (that is, the high % error from the small difference in masses) proved more challenging.
