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Primary General Studies, Science and Technology, Paper 4: sound, parallel circuits and mass
Primary General Studies, Science and Technology, Paper 4: sound, parallel circuits and mass
Ten items on sound in a vacuum, conductors and insulators, like poles, thermal expansion, parallel voltage, independent branches, units of electricity, opposite forces, density, mass and weight.
Focus Sound needs a medium and cannot travel in a vacuum; copper conducts and plastic insulates; like poles repel; a thermometer uses thermal expansion; parallel keeps the voltage and adds capacity; parallel branches are independent; units are kilowatts times hours; opposite forces subtract; density is mass over volume; mass does not change with place.
01 Paper details (check answers afterwards)
| Item | Detail |
|---|---|
| Questions | 10 |
| Suggested time | 25 |
| Difficulty mix | Foundation 4 · Intermediate 3 · Challenge 2 · Error redo 1 |
| Chapter | Chapter: Primary General Studies: Science and Technology |
| Level | P4 to P6 |
02 Questions (10 items)
- FoundationWhy can two astronauts standing face to face on the Moon not hear each other?
- FoundationA cable has a copper core and a plastic cover. What does each part do?
- FoundationWhat happens when the N pole of one magnet is brought near the N pole of another?
- FoundationThe liquid in a thermometer rises and falls with temperature. Which property does this use?
- IntermediateFour 1.5 V cells are connected in parallel. What is the total voltage?
- IntermediateTwo bulbs are connected in parallel and one burns out. What happens to the other?
- IntermediateA 60 W fan runs for 3 hours. How many units of electricity does it use?
- ChallengeOne person pulls 20 N to the right and another pulls 8 N to the left. What is the resultant force and its direction?
- ChallengeAn iron block has a mass of 200 g and a volume of 25 cm3. What is its density, and will it float or sink in water?
- Error redoA classmate says the same iron ball has both less mass and less weight on the Moon. Is this correct?
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | The Moon has almost no air, so there is no medium to carry the sound to the other person. | Sound needs a medium such as air, water or a solid; a vacuum carries no sound at all. |
| 2 | The copper core conducts the current to the appliance, and the plastic cover insulates so nobody gets a shock. | Metals such as copper and iron conduct, while plastic and rubber insulate the part that carries current. |
| 3 | The two poles repel, so the magnets push apart. | Like poles repel and unlike poles attract, so N to N or S to S pushes the magnets apart. |
| 4 | Thermal expansion: the liquid expands and rises when warm, and contracts and drops when cool. | Most substances expand when heated and contract when cooled, which is how a thermometer works. |
| 5 | It is still 1.5 V. Parallel connection adds capacity and running time, not voltage. | Parallel keeps the voltage and raises capacity; only a series connection adds the voltages up. |
| 6 | It keeps lighting, because each parallel branch has its own path for the current. | Parallel branches are independent, while one break in a series circuit stops them all. |
| 7 | 0.18 units, that is 0.18 kWh. | Units are kilowatts times hours: 60 W is 0.06 kW, so three hours use 0.18 units. |
| 8 | The resultant is 12 N to the right. | Opposite forces subtract, and the resultant points the same way as the larger force. |
| 9 | Its density is 8 g/cm3, which is more than water, so it sinks. | Density is mass divided by volume, and anything above 1 g/cm3 sinks in water. |
| 10 | No. The mass stays the same; only the weight is smaller because the Moon pulls with less gravity. | Mass is the amount of matter and does not change with place; weight is gravity pulling and varies by planet. |
04 What to do after marking
- After marking, redo only the wrong items and write down which step went wrong (formula, unit, or misread number).
- Repeat the same item two days later; move to the next paper only when both attempts are correct.
- Parents only need the answer and note columns; there is no need to explain every item.
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Questions and answers are written originally by the TutorZone team and are not taken from any school, publisher or examination authority paper. Every value is checked by computer.
