PH03-08 Physics Coming soon
Moments and the principle of moments (triple)
PH03-08
This lesson is coming soon.
In this lesson
Use moment = force x perpendicular distance, and the principle of moments, to find a missing force or distance on a balanced object.
What it covers
- ONE LINE of recap and no more: a force can do something other than push an object along - it can turn it. The shared spine from PH03-01 to PH03-07 is assumed and is never re-taught
- A moment as the TURNING EFFECT of a force about a pivot
- The pivot named and marked on every single diagram before any number appears
- Moment of a force = force x distance: newton metres, newtons and METRES
- The distance is the PERPENDICULAR distance from the pivot to the LINE OF ACTION of the force - drawn as a construction, not read off the picture
- What that means when the force is not at right angles to the object, described qualitatively
- Clockwise and anticlockwise, decided about the marked pivot and said out loud every time
- The principle of moments: for a balanced object, the total clockwise moment equals the total anticlockwise moment
- Finding a missing force or a missing distance by setting those two sums equal and rearranging
- Centimetres and millimetres converted to metres before substituting, on their own CONVERT line
- Reading the unit: newton metres, and why that is not a joule
Key words
For: AQA GCSE 8463, Edexcel GCSE 1PH0, OCR GCSE J249
On the specification
| Board | Spec | Statement |
|---|---|---|
| AQA GCSE 8463 | 4.5.4 | Moments, levers and gears |
| Edexcel GCSE 1PH0 | 9.6P | Describe situations where forces can cause rotation |
| Edexcel GCSE 1PH0 | 9.7P | Recall and use the equation: moment of a force (newton metre, N m) = force (newton, N) × distance normal to the direction of the force (metre, m) |
| Edexcel GCSE 1PH0 | 9.8P | Recall and use the principle of moments in situations where rotational forces are in equilibrium: the sum of clockwise moments = the sum of anti-clockwise moments for rotational forces in equilibrium |
| Edexcel GCSE 1PH0 | 9.9P | Explain how levers and gears transmit the rotational effects of forces |
| OCR GCSE J249 | P2.3k | Describe examples in which forces cause rotation |
| OCR GCSE J249 | P2.3l | Define and calculate the moment of a force |
| OCR GCSE J249 | P2.3m | Explain how levers and gears transmit the rotational effects of forces |
| OCR GCSE J249 | PM2.3vi | Recall and apply: moment of a force (N m) = force (N) × distance (m) (normal to direction of the force) |
For teachers
This GCSE Physics lesson teaches moments and the principle of moments (triple). By the end, students should be able to use moment = force x perpendicular distance, and the principle of moments, to find a missing force or distance on a balanced object. It works through four worked examples and the mistakes examiners report, and suits Foundation and Higher tier students.