AQA · GCSE · Physics
Course version: 8463 · Version from Sept 2016
A simple lever and a simple gear system can both be used to transmit the…
Full specification wording
Moments, levers and gears (physics only): A simple lever and a simple gear system can both be used to transmit the rotational effects of forces.
A lever and a gear train both take a turning effect in at one place and deliver it at another, usually with a different size of force.
Checked against the AQA 8463 specification (opens in a new tab) on .
- Point 6 of 7
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
A lever and a gear train both take a turning effect in at one place and deliver it at another, usually with a different size of force. A lever is a rigid bar turning about a pivot: because the moments on the two sides must match, a small effort a long way from the pivot balances a large load close to it, so a crowbar, a wheelbarrow and a pair of scissors all multiply force. The price is distance, since the effort end moves much further than the load end. Gears do the same job between two shafts. Their teeth mesh so that neither slips and the wheels turn in opposite directions, and the moment delivered depends on the size of the gear the force finally acts on. Neither device creates energy; both trade force against distance or speed.
What earns the marks
- A lever described as a rigid bar turning about a pivot.
- A small effort at a large distance balancing a large load at a small distance.
- Gears transmitting the turning effect between shafts through meshed teeth.
- Stating that the energy transferred is not increased, so force is gained at the cost of distance or speed.
Common mistakes and how to put them right
Saying a lever or a gear makes more energy or increases the work done.
Forgetting that meshed gears turn in opposite directions.
Describing a lever without identifying its pivot.
Claiming a longer lever increases the weight of the load rather than the moment available.
Exam tips
- Every lever answer needs the pivot, the effort, the load and the two distances.
- State the trade-off - more force, less movement - because it separates good answers from vague ones.
Try the lesson
The start of the Moments, levers and gears (physics only): A simple lever and a simple gear system can both be used to transmit the rotational effects of forces. lesson, made from checked teaching notes for this specification point.
Have a go first
A lever is used to lift a heavy load. Which statement describes how the lever transmits the rotational effect of the force applied to it?
Listen
A lever and a gear train both take a turning effect in at one place and deliver it at another, usually with a different size of force. A lever is a rigid bar turning about a pivot: because the moments on the two sides must match, a small effort a long way from the pivot balances a large load close to it, so a crowbar, a wheelbarrow and a pair of scissors all multiply force. The price is distance, since the effort end moves much further than the load end. Gears do the same job between two shafts. Their teeth mesh so that neither slips and the wheels turn in opposite directions, and the moment delivered depends on the size of the gear the force finally acts on. Neither device creates energy; both trade force against distance or speed. A strong answer earns marks for these points. a lever described as a rigid bar turning about a pivot. a small effort at a large distance balancing a large load at a small distance. gears transmitting the turning effect between shafts through meshed teeth. stating that the energy transferred is not increased, so force is gained at the cost of distance or speed. Exam tip: Every lever answer needs the pivot, the effort, the load and the two distances.
Key words
Say what each word means before you turn the card.
levers
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gears
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force multiplier
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transmitting moments
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See every definition
- levers
- A rigid bar turning about a pivot, where a small effort a long way from the pivot balances a large load close to it.
- gears
- Wheels whose teeth mesh so that neither slips and the turning effect is transmitted between two shafts, turning in opposite directions.
- force multiplier
- A device that trades force against distance or speed, since the energy transferred is not increased.
- transmitting moments
- Taking a turning effect in at one place and delivering it at another, usually with a different size of force.
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