Cambridge International AS Level Physics
Answers to self-assessment questions
Answers to SAQs
Chapter P1
13
h / cm
2
2
d / cm d / cm
1.0
18.0
324
1Probably 50 Ω, 100 Ω, 200 Ω, 300 Ω, 400 Ω,
500 Ω. They cover the whole range with
roughly equal differences.
2.5
28.4
807
4.0
35.8
1280
5.5
41.6
1730
2a
7.0
47.3
2240
9.0
53.6
2870
b
14 a
d2 / cm2
3000
+
+
2000
3Left-hand diagram indicates systematic error.
Right-hand diagram indicates random error.
4Pointer does not indicate zero when load = 0;
scale incorrectly calibrated.
51 mm at either end = ±2 mm; but if several
measurements are required end-to-end and
the tape measure is not long enough, this will
increase the uncertainty. This assumes the
tape measure is drawn tightly but does not
stretch in length.
6±0.5 °C or ±1.0 °C
7Between ±0.2 cm and ±1 cm.
8Between ±0.2 s and ±0.5 s.
9
a
b
c
d
Average = (20.6 + 20.8)/2 = 20.7 ± 0.1
Average = (20 + 30 + 36)/3 = 29 ± 8
Average = (0.6 + 1.0 + 0.8 + 1.2)/4 = 0.9 ± 0.3
Average = (20.5 + 20.5)/2 = 20.5 ± 0.1
10 ±0.8%
11 a ±5.7% or 6%
b The pendulum is moving during
measurement.
+
1000
0
+
+
0
2
4
6
h / cm
8
10
b Gradient = 320 cm; y-intercept = 0 cm2
approx.
15 If T is proportional to m, then T = km.
6.3
Two values of k are 4.6
0.9 = 5.1 and 1.2 = 5.25.
The % difference in the k values is
0.15 × 100 = 2.9%.
5.1
The percentage difference in the T value is
0.2 × 100 = 4.3%.
4.6
The criterion is that the % difference in the k
values should be less than the % difference
in the raw data for proportionality to be
shown. This has been shown, so the data is
consistent with a proportional relationship.
2
16 Two values of k = tr are 3.41 and 3.0.
They differ by about 14%. The percentage
uncertainty in r is 3%. Since the %
uncertainty in the k values is larger than the
% uncertainty in the readings, the data is not
consistent with a proportional relationship.
12 ±0.25 V
Cambridge International AS and A Level Physics © Cambridge University Press 2014