Question 1
(a) A student measures the diameter of some identical steel balls. Fig. 1.1 shows the arrangement she uses. (Subtopic Code: 1.1)
(i)Using the ruler in Fig. 1.1, determine the distance AB on Fig. 1.1.
▶️Answer/Explanation
4.3 cm
(ii)Use the distance AB to determine the diameter of one steel ball.
▶️Answer/Explanation
0.54 cm
(b) The mass of some steel balls is 54 g and the total volume of these steel balls is 6.9 cm3.
Calculate the density of the steel. (Sub-topic Code: 1.4)
▶️Answer/Explanation
7.8 g/cm3
Question 2
(a) Fig. 2.1 shows the speed–time graph for a cyclist.(Sub-topic Code: 1.2)
(i) In Fig. 2.1, the sections ST, TW, WX, XY, and YZ indicate stages of the cyclist’s journey. State one section which shows the cyclist moving with:
▶️Answer/Explanation
ST or WX
(ii)
▶️Answer/Explanation
XY
(iii)
▶️Answer/Explanation
TW or XY
(b) Calculate the distance travelled by the cyclist in section ST. (Sub-topic Code: 1.2)
▶️Answer/Explanation
100 m
(c) Fig. 2.2 shows the horizontal forces on a cyclist. (Sub-topic Code: 1.5)
(i) Calculate the size of the resultant force on the cyclist.
▶️Answer/Explanation
60 N
(ii) State the effect, if any, of the resultant force on the motion of the cyclist.
▶️Answer/Explanation
The cyclist accelerates or increases speed.
Question 3
A student has a battery-powered torch. Fig. 3.1 shows the torch.
(a) Fig. 3.2 shows the energy transfers when the torch is switched on. The diagram is incomplete.(Subtopic Code: 1.7)
Show the energy transfers in the torch by completing the labels on Fig. 3.2.
▶️Answer/Explanation
Electrical energy → Chemical energy (100 J)
Chemical energy → Light energy (70 J)
Chemical energy → Thermal energy (30 J)
(b) The weight of the torch is 8.5 N. The student lifts the torch a vertical distance of 0.80 m to place it on a shelf. (Subtopic Code: 1.7)
Calculate the work done on the torch by the student.
▶️Answer/Explanation
6.8 J
(c) The student places the torch on its base on a shelf. The area of the base of the torch is 44 cm2. The weight of the torch is 8.5 N. (Subtopic Code: 1.8)
Calculate the pressure on the shelf due to the torch.
▶️Answer/Explanation
0.19 N/cm2
Question 4
A student has a block of solid metal at room temperature.
(a) (i) Describe the arrangement, separation, and motion of the particles in the solid metal.(Subtopic Code: 2.1)
▶️Answer/Explanation
– Particles are fixed in position.
– Particles are arranged in a regular pattern.
– Particles vibrate about fixed positions.
– Particles are close together.
(ii) The student cools the block of metal in a freezer. State the effect, if any, of cooling on the kinetic energy of the particles in the block of metal.
▶️Answer/Explanation
The kinetic energy of the particles decreases.
(b) (i) State the name of the temperature at which particles have the least kinetic energy. (Subtopic Code: 2.1)
▶️Answer/Explanation
Absolute zero
(ii) State the value of temperature at which particles have the least kinetic energy. Include the unit.
▶️Answer/Explanation
−273 °C or 0 K
(c) The metal block emits thermal radiation from its surface. (Subtopic Code: 2.3)
State two features of a surface that is a good emitter of thermal radiation.
▶️Answer/Explanation
1. Black or dark in color.
2. Dull or rough in texture.
Question 5
An observer stands at P and looks into a rock quarry. A small explosion takes place at X in the quarry.
Fig. 5.1 shows the situation.
(a) The observer first hears the sound from the explosion 1.8 s after the explosion occurs. (Subtopic Code: 3.4)
The speed of the sound is 340 m/s.
(i) Calculate the distance XP from the explosion at X to the observer at P.
▶️Answer/Explanation
610 m
(ii) The observer then hears a quieter sound from the explosion.
Suggest how the quieter sound waves reach the observer.
▶️Answer/Explanation
The quieter sound waves reach the observer as an echo. The sound waves reflect off the rocks or the bottom of the quarry (YZ or Z) and travel back to the observer.
(b) Before the explosion, a warning siren produces a sound. The wavelength of the sound is 0.28 m. (Subtopic Code: 3.4)
The speed of the sound is 340 m/s.
Calculate the frequency of the sound.
▶️Answer/Explanation
1200 Hz
Question 6
Fig. 6.1 shows light waves passing from air into a glass block.
(a) (i) State the name of the process shown in Fig. 6.1 as the wavefronts enter the glass block. (Subtopic Code: 3.2)
▶️Answer/Explanation
Refraction
(ii) State two changes in the light waves as they pass from air into glass.
▶️Answer/Explanation
1. The speed of the light waves decreases.
2. The wavelength of the light waves decreases.
(b) Fig. 6.2 shows a ray of red light travelling through a glass fibre. The glass fibre is made of solid glass. (Subtopic Code: 3.2)
State and explain how the ray of red light travels through the glass fibre as shown in Fig. 6.2.
▶️Answer/Explanation
The ray of red light undergoes total internal reflection as it travels through the glass fibre. This occurs because the light is travelling from a more dense medium (glass) into a less dense medium (air) at an angle greater than the critical angle. The light reflects off the inner surface of the glass fibre and continues to travel along the fibre.
Question 7
A student uses a permanent magnet to lift some unmagnetised nails. Some of the nails are made of iron and some are made of steel. Fig. 7.1 shows the magnet lifting the nails.
(a) (i) Each nail lifts the nail below it by induced magnetism.(Subtopic Code: 4.1)
Describe what is meant by induced magnetism.
▶️Answer/Explanation
Induced magnetism occurs when a magnetic material (like iron or steel) becomes magnetised when placed in a magnetic field. The material temporarily acquires magnetic properties, such as having a north and south pole, due to the influence of the external magnetic field.
(ii) The student leaves the nails attached to the magnet for several hours, then removes the magnet. State a difference between a magnetic property of the iron nails and of the steel nails.
▶️Answer/Explanation
The iron nails lose their magnetism quickly after the magnet is removed (they are temporary magnets), while the steel nails retain their magnetism for a longer time (they are permanent magnets).
(b) A metal wire XY is connected to a voltmeter. The wire is placed between the poles of a permanent magnet. Fig. 7.2 shows the arrangement. (Subtopic Code: 4.5)
(i) State the reading on the voltmeter when the wire is stationary between the poles.
▶️Answer/Explanation
Zero (0) reading.
(ii) Give a reason for the reading on the voltmeter when the wire is moving in the direction shown in Fig. 7.2.
▶️Answer/Explanation
When the wire moves, it cuts through the magnetic field lines, inducing an electromotive force (emf) in the wire. This emf causes a current to flow, which is detected by the voltmeter.
Question 8(Subtopic Code: 4.2)
A student uses the circuit in Fig. 8.1 to measure the resistance of the heater in the circuit.
(a) The symbols for the meters in Fig. 8.1 are incomplete. (Subtopic Code: 4.2)
Complete the symbols for the two meters by writing in the circles in Fig. 8.1.
▶️Answer/Explanation
The first meter is an ammeter (symbol: A).
The second meter is a voltmeter (symbol: V).
(b) The current in the heater is 1.4 A and the potential difference (p.d.) across the heater is 8.0 V. (Subtopic Code: 4.2)
Calculate the resistance of the heater.
▶️Answer/Explanation
5.7 Ω
(c) The heater is switched on for 30 s. The current in the heater is 1.4 A and the p.d. across it is 8.0 V. (Subtopic Code: 4.2)
Calculate the electrical energy transferred by the heater during the 30 s.
▶️Answer/Explanation
340 J
Question 9
A student has a desktop computer that connects to the 240 V a.c. mains electrical supply. Fig. 9.1 shows the desktop computer.
(a) The desktop computer has an on-off switch in one of the wires that connect it to the mains supply. (Subtopic Code: 4.5)
State and explain which wire includes the switch.
▶️Answer/Explanation
The switch is in the live wire. This is because the live wire carries the high voltage from the mains supply, and switching it off ensures the computer is disconnected from the high voltage, making it safe to handle.
(b) The desktop computer uses a transformer to change the 240 V a.c. voltage to a 12 V a.c. voltage. (Subtopic Code: 4.5)
(i) State the name of this type of transformer.
▶️Answer/Explanation
Step-down transformer
(ii) Describe the construction of this transformer. You may include a labelled diagram.
▶️Answer/Explanation
A step-down transformer consists of:
– A soft iron core to provide a low-reluctance path for the magnetic flux.
– Two coils of wire: the primary coil (connected to the 240 V a.c. supply) and the secondary coil (connected to the 12 V output).
– The number of turns in the primary coil is greater than the number of turns in the secondary coil, which reduces the voltage from 240 V to 12 V.
– The transformer operates on the principle of electromagnetic induction, where a changing magnetic field in the primary coil induces a voltage in the secondary coil.
Question 10
Iodine-131 is a radioactive isotope of the element iodine. Fig. 10.1 shows the nuclide notation for a nucleus of iodine-131.
(a) (i) Determine the number of protons in one nucleus of iodine-131. (Subtopic Code: 5.2)
number of protons =
▶️Answer/Explanation
53
(ii) Determine the number of neutrons in one nucleus of iodine-131.
number of neutrons =
▶️Answer/Explanation
78
(b) When a nucleus of iodine-131 decays, it emits a beta (β)-particle and a gamma (γ) ray.(Subtopic Code: 5.2)
State the nature of a beta-particle and a gamma ray.
▶️Answer/Explanation
A beta-particle is a high-energy electron emitted from the nucleus during beta decay.
A gamma ray is a high-energy electromagnetic wave emitted from the nucleus.
(c) A sample contains 1.6 mg of iodine-131. (Subtopic Code: 5.2)
The half-life of iodine-131 is 8.0 days.
Calculate the mass of iodine-131 remaining in the sample after 24.0 days.
mass of iodine-131 remaining =
▶️Answer/Explanation
0.2 mg
Question 11
Fig. 11.1 shows the Sun and the four innermost planets, A, B, C, and D, of the Solar System.
(a) In Table 11.1, write the names of the innermost planets. One is done for you. (Subtopic Code: 6.1)
| Planet | Name of Planet |
|---|---|
| A | …… |
| B | Venus |
| C | …… |
| D | …… |
▶️Answer/Explanation
A: Mercury
B: Venus
C: Earth
D: Mars
(b) Describe how the four innermost planets of the Solar System were formed. (Subtopic Code: 6.1)
▶️Answer/Explanation
The four innermost planets (Mercury, Venus, Earth, and Mars) were formed from a rotating disk of dust and gas surrounding the young Sun. Over time, particles in the disk collided and stuck together, forming larger bodies called planetesimals. These planetesimals further collided and accreted, eventually forming the rocky, terrestrial planets. The process was driven by gravity, which caused the material to clump together and grow into planets.