Physics 9702/33 February/March 2019: question paper and mark scheme
Cambridge AS & A Level Physics (9702), Paper 3 Advanced Practical Skills 1, February/March 2019. Read both free below, or download them. Done the paper? Get it marked by AI against this mark scheme.
In this experiment, you will investigate a pendulum with a mass fixed at each end.
(a) • Assemble the apparatus with the nail passing through the third hole from C, as shown in
Fig. 1.1.
• Ensure that the nail is held securely in the clamp.
mass stand wooden strip clamp holes boss
x c
mark labelled C nail (held in clamp)
bench
Fig. 1.1
• The distance between the nail and C is x, as shown in Fig. 1.1.
Measure and record x.
x = …… cm [1]
(b) • Push the bottom of the strip horizontally through a distance of approximately 5 cm.
Release the strip so that it oscillates.
• Determine the period T of these oscillations.
T = …… s [2]
(c) Change x by positioning the nail in a different hole and repeat (b). Repeat until you have six sets of values of x and T.
1
Record your results in a table. Include values of and T 2 in your table. x
[9]
1
(d) (i) Plot a graph of T 2 on the y-axis against on the x-axis. [3]
x
(ii) Draw the straight line of best fit. [1]
(iii) Determine the gradient and y-intercept of this line.
gradient = ……
y-intercept = ……
[2]
(e) It is suggested that the quantities T and x are related by the equation a
T2= +b x where a and b are constants.
Use your answers in (d)(iii) to determine the values of a and b.
Give appropriate units.
a = ……
b = ……
[2]
[Total: 20]
You may not need to use all of the materials provided.
Mark scheme
1(a) value of x to nearest mm and in range 4.5 to 5.5 cm 1
1(b) value of T in range 1.50 s to 2.50 s 1
repeat readings – at least two values of at least 5T 1
1(c) six sets of readings of x and T with correct trend and without help from supervisor scores 4 marks, five sets scores 3 marks 4
etc.
range: 1
xmin ⩽ 2.5 cm and xmax ⩾ 13.5 cm
column headings: 1
each column heading must contain a quantity and a unit
the presentation of quantity and unit must conform to accepted scientific convention. e.g. T 2 / s2
consistency: 1
all values of raw times must be given to the nearest 0.1 s or all values to the nearest 0.01 s
significant figures: 1
significant figures for every value of 1 / x same as, or one greater than, the s.f. of x as recorded in table
calculation: 1
values of 1 / x calculated correctly
1(d)(i) axes: 1
sensible scales must be used, no awkward scales (e.g. 3:10)
scales must be chosen so that the plotted points occupy at least half the graph grid in both x and y directions
scales must be labelled with the quantity which is being plotted
scale markings should be no more than 3 large squares apart
plotting of points: 1
all observations must be plotted on the grid
diameter of plotted points must be ⩽ half a small square (no blobs)
plots must be accurate to within half a small square in both x and y directions
quality: 1
all points in the table must be plotted (at least 5) for this mark to be awarded. Scatter of plots must be no more than
± 0.05 cm–1 from a straight line in the 1 / x direction
1(d)(ii) line of best fit: 1
judged by balance of all points on the grid (at least 5) about the candidate’s line. There must be an even distribution of points
either side of the line along the full length
one anomalous point is allowed only if clearly indicated (i.e. circled or labelled) by the candidate
lines must not be kinked or thicker than half a small square
1(d)(iii) gradient: 1
the hypotenuse of the triangle used must be greater than half the length of the drawn line
method of calculation must be correct
both read-offs must be accurate to half a small square in both the x and y directions
y-intercept: 1
Either
correct read-off from a point on the line substituted into y = mx + c or an equivalent expression, with read-off accurate to half a s
square in both x and y directions
Or
intercept read directly from the graph, with read-off at x = zero accurate to half a small square in y direction
1(e) a equal to candidate’s gradient, and b equal to candidate’s intercept, and values are not written as fractions 1
unit for a is correct and consistent with value 1
unit for b is correct
In this experiment, you will investigate the relationship between the pressure in a balloon and its diameter.
(a) • You are provided with two partially inflated balloons. Place the larger balloon on the bench with its neck at the side, as shown in Fig. 2.1.
• Put pieces of modelling clay around the balloon to stop it rolling, as shown in Fig. 2.1.
balloon
modelling
B clay
tray
bench
Fig. 2.1
• The diameter of the balloon is B, as shown in Fig. 2.1.
Measure and record B.
B = …… [1]
(b) • Wet a small area on the top of the balloon with a damp paper towel.
• Balance the transparent block on the top of the balloon, as shown viewed from above in
Fig. 2.2.
tape handle
transparent block
Fig. 2.2
• The contact patch will be visible, as shown in Fig. 2.3.
d
contact patch
Fig. 2.3
• The diameter of the contact patch is d, as shown in Fig. 2.3.
Measure and record d.
d = …… [2]
(c) Estimate the percentage uncertainty in your value of d.
percentage uncertainty = …… [1]
(d) Calculate the pressure P in the balloon using the relationship
4mg
P= πd 2 where g = 9.81 N kg–1 and m is the mass of the transparent block written on the card.
P = …… Nm–2 [2]
(e) Justify the number of significant figures you have given for your value of P.
[1]
(f) Repeat (a), (b) and (d) using the smaller partially inflated balloon.
B = ……
d = ……
P = …… Nm–2
[3]
(g) It is suggested that the relationship between B and P is k
P=
B where k is a constant.
(i) Using your data, calculate two values of k.
first value of k = ……
second value of k = ……
[1]
(ii) Explain whether your results support the suggested relationship.
[1]
(h) (i) Describe four sources of uncertainty or limitations of the procedure for this experiment.
1. ……
2. ……
3. ……
4. ……
[4]
(ii) Describe four improvements that could be made to this experiment. You may suggest the use of other apparatus or different procedures.
1. ……
2. ……
3. ……
4. ……
[4]
[Total: 20]
Mark scheme
2(a) value for B, with unit 1
2(b) measured value(s) for d, with unit, to nearest mm 1
evidence of repeat readings 1
2(c) absolute uncertainty in d value ⩾ 0.2 cm and correct method of calculation to obtain percentage uncertainty. 1
if several readings have been taken, then the absolute uncertainty can be half the range if the working is clearly shown (but
not zero if values are equal)
2(d) calculation of P correct 1
POT of P value matches unit 1
2(e) justification based on s.f. in d, m and g 1
2(f) value for second B 1
value for second d 1
Quality: 1
d smaller for smaller B
2(g)(i) two values of k calculated correctly 1
2(g)(ii) sensible comment relating to the calculated values of k, testing against a criterion specified by the candidate 1
2(h)(i) two k values are not enough to draw a valid conclusion 4 max
difficult to measure B with reason, e.g. pressing on balloon / ruler scale doesn’t start at zero / parallax
difficult to balance Perspex block on balloon / balloon kept moving
difficult to measure d with reason, e.g. not circular / changes when block touched / parallax / refraction changes apparent size
difficult to see (edges of) contact patch (clearly)
2(h)(ii) take more readings and plot a graph / calculate more k values and compare 4 max
workable method of reducing parallax for B e.g. callipers
fix balloon in place with tape / glue / Blu-tack / trap between blocks at sides
grid on block / travelling microscope / thinner block
use contrasting colours for balloon and liquid
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On this page, free: the mark scheme for AS & A Level Physics 9702/33, February/March 2019 (9702_m19_ms_33), and the question paper (9702_m19_qp_33), to read or download, with each question's marking points written out underneath.
How many marks is 9702/33 out of?+
Physics 9702/33 for February/March 2019 is out of 40 marks, with 2 hours to answer it, across 2 questions.
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