A-LevelPhysicsPhysical quantities and units9702/33 · Oct/Nov 2021 · Q220 Marks

In this experiment, you will investigate the time taken for filter papers to fall in air.

(a)(i)• You have been provided with filter papers of two different sizes. • Take one sheet of the smaller filter paper. • The diameter of one sheet of filter paper is d, as shown in Fig. 2.1. d filter paper Fig. 2.1 Measure and record d. d = ___________ cm[2]
(a)(ii)Calculate the area A of the filter paper using A = πα²/4 A = ___________ cm²[1]
(a)(iii)Justify the number of significant figures that you have given for your value of A.[1]
(b)(i)• Set up the apparatus as shown in Fig. 2.2. -six sheets of filter paper clamp boss stand metre rule bench Fig. 2.2 • Hold the six sheets of the smaller filter paper at the top of the metre rule, as shown in Fig. 2.2. • Release the filter papers and start the stop-watch. • The time between release and the filter papers hitting the bench is t. Measure and record t. t = ___________ s[2]
(b)(ii)Estimate the percentage uncertainty in t. Show your working. percentage uncertainty = [1]
(b)(iii)Measure and record the total mass m of the sheets of smaller filter paper. m = ___________[1]
(c)(i)Repeat (a)(i) and (a)(ii) using one of the larger sheets of filter paper. d = ___________ cm A = ___________ cm²[1]
(c)(ii)Using two sheets of the larger filter paper, repeat (b)(i) and (b)(iii). t = ___________ s m = ___________[1]
(d)(i)It is suggested that the relationship between t, m and A is kt = mA where k is a constant. Using your data, calculate two values of k. first value of k = second value of k = [1]
(d)(ii)Explain whether your results support the suggested relationship.[1]
(e)(i)Describe four sources of uncertainty or limitations of the procedure for this experiment.[4]
(e)(ii)Describe four improvements that could be made to this experiment. You may suggest the use of other apparatus or different procedures.[4]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2021). The mark or mark type is shown in brackets.

[1] d = 11.0 ± 0.5 cm.
[1] Raw value(s) of d recorded to the nearest millimetre.
[1] A calculated correctly.
[1] Number of significant figures in A is linked to the number of significant figures in d.
[1] Value of t in the range 0.5 ≤ t ≤ 1.0s and given to 0.1 s or better.
[1] Repeated measurement of t.
[1] Percentage uncertainty based on an absolute uncertainty in the range 0.2-0.5s. If repeated readings have been taken, then the uncertainty can be half the range (but not zero) if working is clearly shown. Correct method of calculation to find percentage uncertainty.
[1] Mass in the range 2.0-10.0g and measured to the nearest 0.1 g or better and with unit.
[1] Second value of d.
[1] Second value of t is larger than the first value of t.
[1] Two values of k calculated correctly. The final values must not be written as fractions.
[1] Valid comment consistent with the calculated values of k, testing against a criterion stated by the candidate.
[1] Two readings are not enough to draw a (valid) conclusion (not “not enough for accurate results”, “few readings").
[1] Difficulty with filter paper at the start, e.g. paper not horizontal/paper too high to view against ruler/parallax in viewing start position/paper held by hand which moves/metre rule not vertical.
[1] Difficult to start stop-watch and release filter paper at the same time.
[1] Problem with fall of filter paper with a reason, e.g. paper does not fall vertically/erratic path/hits boss or stand/misses bench/papers separate while falling.
[1] Difficulty with judging when to stop the stop-watch with a reason, e.g. difficult to align head at bench level/papers arrive separately.
[1] Times are small so large error/uncertainty (in t) or high percentage uncertainty in t.
[1] Take more readings and plot a graph or take more readings and compare k values (not “repeat readings" on its own).
[1] Improved method to hold/release filter paper, e.g. horizontal bar level with top of rule or use a set square with detail, e.g. use set square between bench and ruler or use plumb-line.
[1] Video/record/film with timer/frame-by-frame.
[1] Use more filter papers/heavier or thicker paper/glue together or switch off air-conditioning/close windows/use a wind shield.
[1] Use a pressure sensor below/position sensor above or below.
[1] Use a greater distance to fall through or use larger diameters/use fewer papers/use lighter papers/use thinner papers (Credit once only if heavier papers suggested for D and lighter papers suggested for F.)