PH03-09 Physics Coming soon
Levers and gears (triple)
PH03-09
This lesson is coming soon.
In this lesson
Explain how a lever or a gear multiplies the turning effect of a force, using the moment equation on both sides of the pivot.
What it covers
- ONE LINE of recap and no more: M = F d and the principle of moments come from PH03-08 and are assumed, not re-taught
- A LEVER: effort, load and pivot named on the diagram, and the three arrangements the pivot can take
- Why a longer effort arm needs a smaller effort force for the same moment - read straight off M = F d
- The trade: the effort end moves further than the load end, so nothing is got for free
- Everyday levers a viewer has used: a spanner, a crowbar, a wheelbarrow, scissors, a bottle opener, the forearm
- GEARS: teeth meshing, a small gear driving a large one and the reverse
- A gear treated as a lever whose arm is its radius, with the moment transmitted at the point where the teeth meet
- What a gear train changes: turning effect up and rotation rate down, or the other way round
- The direction reversal at every mesh, and saying it out loud
- Calculating with M = F d on both sides of a lever or a gear pair to find a missing force or distance
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 levers and gears (triple). By the end, students should be able to explain how a lever or a gear multiplies the turning effect of a force, using the moment equation on both sides of the pivot. It works through four worked examples and the mistakes examiners report, and suits Foundation and Higher tier students.