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S3 Science: Forces, Motion, Speed-Time Graphs and Net Force (Paper 4: mistake clinic)
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S3 Science: Forces, Motion, Speed-Time Graphs and Net Force (Paper 4: mistake clinic)
This last paper revisits three frequent errors: unit conversion, the direction of net force and mass against weight.
Direct answers Spend three seconds checking those three points after each question, which beats rereading the notes.
01 Paper details (check answers afterwards)
| Item | Detail |
|---|---|
| Questions | 10 |
| Suggested time | 20 |
| Difficulty mix | Foundation 3 · Intermediate 3 · Challenge 3 · Error redo 1 |
| Chapter | Chapter: S3 Science: Forces, Motion, Speed-Time Graphs and Net Force |
| Level | S3 Science |
02 Questions (10 items)
- FoundationHow many m/s is 54 km/h?
- FoundationTravelling at 12 m/s for 8 seconds covers how much distance?
- FoundationForces of 18 N and 7 N act in opposite directions. What is the net force?
- IntermediateWhat net force gives a 3 kg object an acceleration of 4 m/s²?
- IntermediateA net force of 24 N acts on 6 kg. What is the acceleration?
- IntermediateA horizontal line on a distance-time graph shows what?
- ChallengeCovering 300 metres in 60 seconds gives what average speed?
- ChallengeHow is the direction of friction decided?
- ChallengeWhat is the net force on an object moving at constant velocity?
- Error redoA student writes 30 m/s as 30 km/h. What is the correct value?
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | 15 m/s | Dividing 54 by 3.6 gives 15. |
| 2 | 96 m | Multiplying 12 by 8 gives 96 metres. |
| 3 | 11 N in the direction of the 18 N force | Subtracting gives 11 newtons in the direction of the larger force. |
| 4 | 12 N | Using F = ma, 3 times 4 is 12 newtons. |
| 5 | 4 m/s² | Dividing 24 by 6 gives 4. |
| 6 | The object is at rest | The distance stops growing while time passes, so the slope is zero. |
| 7 | 5 m/s | Dividing 300 by 60 gives 5 metres per second. |
| 8 | It opposes the relative motion of the object | Friction resists sliding, so it points against the motion although it can help something start moving. |
| 9 | Zero | Speed and direction are unchanged so the acceleration is zero, which makes the net force zero as well. |
| 10 | 30 m/s equals 108 km/h | Multiplying by 3.6 gives 108, so the two units differ by a factor of 3.6. |
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.
Keep three columns in the error log: question, cause, corrected steps. The three commonest slips here are unconverted units, ignoring direction in net force, and treating mass as weight.Tutor Registration →
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.