Physics 9702 · AS & A Level · Errors and uncertainties
Errors and uncertainties — practice question
A well is 36\,\text{m} deep from ground level to the water surface, as shown in Fig. 1.1. A student wants to determine the depth of the well. To do this, the student intends to let a stone fall down the well and measure the time from the moment the stone is released until the splash is heard when it enters the water.
(a)[2]
Ignore air resistance and assume the stone is released from rest. Calculate the time taken for the stone to drop from ground level to the water surface.
(b)[3]
The stopwatch reading obtained by the student is not the same as the time in (a). Suggest three possible reasons, apart from air resistance, for this discrepancy.
(c)[2]
The student repeats the experiment three times and uses the results to calculate the depth of the well. The values are shown in Table 1.1. The true depth of the well is $36.0\,\text{m}$. Explain why these results may be described as precise but not accurate.
Worked solution & mark scheme
This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Application of $t = \sqrt{\frac{2s}{g}}$” …