MCE Cambridge IGCSETM Physics Full Solutions to Questions in Student’s Book
Chapter 1
Chapter 1
Measurement
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In examinations, the way marks are awarded may be different. References to assessment and/or
assessment preparation are the publisher’s interpretation of the syllabus requirements and may
not fully reflect the approach of Cambridge Assessment International Education.
Chapter Opener [Page 1]
• Typical value in the population
• Length and weight
[Note: The instrument used to weigh the baby is usually calibrated to give readings in grams and
kilograms and not in newtons. This allows ‘weight’ to refer to both weight (N from the scientific
viewpoint) and mass (kg and g from the practical viewpoint)].
• Mass, time, volume, temperature, electric current, energy, etc.
Enrichment (Think) [Page 4]
We can use a thread and a rule. Place one end of the thread at one end of the curved line. Run the thread
a little at a time along the curve line till the end and mark the end point on the thread. Cut the threat at the
mark. Straighten the cut thread along a metre rule and measure its length. This will give the length of the
curved line.
Quick Check [Page 4]
True
Parallax error is caused by placing the eye at the wrong position when taking the reading.
Enrichment (Activity) [Page 8]
Human reaction time is about 0.3–0.5 s for most people. (Answer varies.)
Quick Check [Page 9]
False
The time for one complete oscillation of a simple pendulum is too short to take accurately with a
stopwatch. Therefore, in an experiment, we typically take the total time for say, 10 complete oscillations
and then find the (average) time for one complete oscillation by dividing total time by 10.
Let’s Practise 1.1 [Page 10]
1.
1.0 ´ 10–5 m
2.
(a)
(b)
Parallax error
Level the eye with the bottom of the meniscus
3.
(a)
m3 and cm3
(b)
Take a measuring cylinder containing some water. Record the volume of the water V1.
Use a sinker to immerse the small irregular object in the water inside the measuring cylinder.
Record the volume of the water V2. The volume of the object can be found by V = V2 – V1.
4.
The strip of mirror helps you to check that the image of the needle coincides with the needle when
taking a reading. This ensures that your eyes are positioned directly above the needle. This helps to
prevent parallax error.
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MCE Cambridge IGCSETM Physics Full Solutions to Questions in Student’s Book
5.
Chapter 1
Moving from A to C to B covers only three-quarters of an oscillation. Hence,
3
4T=3s
4
T=3s´3
=4s
Quick Check [Page 12]
True
A vector has both magnitude and direction.
Let’s Practise 1.2 [Page 13]
1.
Scalar quantities are physical quantities that have magnitude only whereas vector quantities are
physical quantities that have both magnitude and direction.
2.
Resultant force = !152 + 202 = √625 = 25 N
tan 𝜃 =
15
= 0.75
20
𝜃 = 36.9°
The resultant force is 25 N, at 36.9° (anticlockwise) from the 20 N.
Let’s Review [Pages 15–16]
Section A: Multiple-choice Questions
1.
B
Since the distance to be measured is more than half a metre, the half-metre rule should not be
used. We can use the metre rule or the measuring tapes. Each instrument has an accuracy of 0.001
m. However, the ten-metre measuring tape is usually used to measure lengths of several metres,
and curved surfaces. Since it is a straight line, the metre rule is more suitable than the one-metre
measuring tape.
2.
D
3.
D
4.
A
For forces acting at right angles to each other, we can use the
Pythagoras’ Theorem to find the magnitude of the resultant force.
Resultant force = !32 + 42 = 5 N
[Note: The tip-to-tail method is used to find the resultant force.
Hence, in the diagram drawn, the 3 N force has shifted.]
Section B: Short-answer and Structured Questions
1.
(a)
(b)
(c)
Length; Five; Metres {[1] for name of physical quantity, [1] for unit}
Time; Two; Seconds {[1] for name of physical quantity, [1] for unit}
Mass; One thousand; Kilograms {[1] for name of physical quantity, [1] for unit}
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MCE Cambridge IGCSETM Physics Full Solutions to Questions in Student’s Book
2.
(a)
(b)
(c)
3.
Chapter 1
Stack 5 matchboxes together. [1] Measure the height and obtain the average height. [1]
Similarly, lay them side by side. Measure and obtain average length and average breadth.
Repeat for height. Then, calculate the volume V = l x b x h [1]
Immerse a weight, for example, a small pendulum bob in and record the volume V1 in a
cylinder filled with water. [1] Immerse the cork with this weight in the cylinder and measure
the volume V2. [1] The volume of the cork stopper can be found by V = V2 – V1. [1]
Fill the bottle with water and empty the water into a measuring cylinder. [1] Repeat a number
of times till the water level in the measuring cylinder is more than half way up. [1] Read the
volume, divide by the number of times the bottle has been filled and emptied.
(a)
[1]
(b)
Length of thread, l/m
Time for 20 oscillations, t/s
Time for 1 oscillation, T/s
T2/s2
0.35
24.1
1.21
1.46
0.65
32.4
1.62
2.62
1.00
40.1
2.01
4.04
1.45
47.5
2.38
5.66
1.95
56.3
2.82
7.95
[1] each for T/s and T2/s2
(c)
Plot a graph of T2 against l.
[1] for axes labels, [1] for data points
and line, [1] for suitable scale
7.0 − 1.0
Gradient of graph = 1.75 − 0.25
6.0
= 1.50 = 4.0 s2/m
(1.75,7.0)
[1] for big triangle on graph, [1] for
answer
&'!
4.0 s2/m =
(
&'!
g=
[1]
&.* +! /= 9.9 m/s2 [1]
(0.25,1.0)
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MCE Cambridge IGCSETM Physics Full Solutions to Questions in Student’s Book
4
Chapter 1
With a suitable scale, such as 1 cm : 500 N, we can use the parallelogram method to
find the resultant force.
Parallelogram method
The tip-to-tail method is acceptable too.
[1] for suitable scale
[1] for correct vector diagram
[1] for answer
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