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Difference between revisions of "Gear"
 
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===Meaning===
 
===Meaning===
 
[[File:BikeGears.png|right|300px|thumb|You can change the gears on a bicycle to make it easier to go up a hill.]]
 
[[File:BikeGears.png|right|300px|thumb|You can change the gears on a bicycle to make it easier to go up a hill.]]
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[[Gear]]s are circular disks with 'teeth' that lock together with other gears to change the force they are being turned with.
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[[Gear]]s are circular disks with 'teeth' that lock together with other [[gear]]s to change how quickly they spin.
  
 
===About Gears===
 
===About Gears===
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|[[File:Gear2.png|center|400px]]
 
|[[File:Gear2.png|center|400px]]
 
|-
 
|-
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| style="height:20px; width:400px; text-align:center;" |The force can be made bigger by turning the small gear. The bigger gear will turn with a bigger force.
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| style="height:20px; width:400px; text-align:center;" |The [[speed]] can be made bigger by turning the larger gear. The small gear will turn more quickly.
 
|}
 
|}
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==Key Stage 3==
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===Meaning===
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[[Gear]]s are circular disks with 'teeth' that can act to increase the [[speed]] or the [[Moment|moment of a force]].
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===About Gears===
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: A small [[gear]] turning a large [[gear]] acts to decrease the [[speed]] and increase the [[moment]].
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: A large [[gear]] turning a small [[gear]] acts to increase the [[speed]] and decrease the [[moment]].
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==Key Stage 4==
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===Meaning===
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[[Gear]]s are circular disks with 'teeth' that can act to increase the [[speed]] or the [[Moment|moment of a force]].
 +
 +
===About Gears===
 +
: The multiplying effect of [[gear]]s can be found by the [[ratio]] of the radii or the number of 'teeth'.
 +
: A [[gear]] with few teeth turning a [[gear]] with many teeth acts to decrease the [[speed]] and increase the [[moment]].
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: A [[gear]] with many teeth turning a [[gear]] few teeth acts to increase the [[speed]] and decrease the [[moment]].
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: The [[force]] on one [[gear]] is equal in [[magnitude]] to the [[force]] applied to the other [[gear]].
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 +
===Example Calculations===
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{| class="wikitable"
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| style="height:20px; width:200px; text-align:center;" |A [[gear]] with radius 50mm is turned with a [[moment]] of 10Nm. This [[gear]] used to turn a second [[gear]] with a radius of 20mm. Calculate the [[moment]] of the second [[gear]].
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| style="height:20px; width:200px; text-align:center;" |A [[gear]] with 45 teeth is turned with a [[moment]] of 25Nm. This [[gear]] used to turn a second [[gear]] with a 63 teeth. Calculate the [[moment]] of the second [[gear]].
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| style="height:20px; width:200px; text-align:center;" |A [[gear]] with 144 teeth is turned with a [[moment]] of 72Nm. This [[gear]] used to turn a second [[gear]] with 60 teeth. Calculate the [[moment]] of the second [[gear]].
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|-
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| style="height:20px; width:200px; text-align:left;" |'''1. State the known quantities'''
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Moment = 10N
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Radius 1 = 50mm = 0.05m
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Radius 2 = 20mm = 0.02m
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| style="height:20px; width:200px; text-align:left;" |'''1. State the known quantities'''
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Moment = 25Nm
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Teeth Ratio = 45:63
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| style="height:20px; width:200px; text-align:left;" |'''1. State the known quantities'''
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Moment = 70Nm
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Teeth Ratio = 144:60
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|-
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| style="height:20px; width:200px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and [[Solve (Maths)|solve]].'''
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<math>M = Fd</math>
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<math> 10 = F \times 0.05</math>
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<math> F = 200N</math>
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An equal [[force]] applies to the second [[gear]].
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<math> M = F \times d</math>
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<math> M = 200 \times 0.02</math>
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<math> M = 4Nm</math>
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| style="height:20px; width:200px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and [[Solve (Maths)|solve]].'''
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<math> M = \frac {25}{45} \times 63</math>
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<math> M = 35Nm</math>
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| style="height:20px; width:200px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and [[Solve (Maths)|solve]].'''
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<math> M = \frac {72}{144} \times 60</math>
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<math> M = 30Nm</math>
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|}
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===References===
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====AQA====
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:[https://www.amazon.co.uk/gp/product/1471851370/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1471851370&linkCode=as2&tag=nrjc-21&linkId=01c69b0ae058f809cf636033e6ba793e ''Gears, page 133, GCSE Physics, Hodder, AQA '']
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:[https://www.amazon.co.uk/gp/product/1782945970/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945970&linkCode=as2&tag=nrjc-21&linkId=a120d24dcc7cc7a58192069a3aafc1d2 ''Gears, page 167, GCSE Physics; The Complete 9-1 Course for AQA, CGP, AQA '']
 +
:[https://www.amazon.co.uk/gp/product/0008158770/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=0008158770&linkCode=as2&tag=nrjc-21&linkId=ec31595e720e1529e49876c3866fff6e ''Gears, page 171, GCSE Physics; Student Book, Collins, AQA '']
 +
:[https://www.amazon.co.uk/gp/product/178294558X/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=178294558X&linkCode=as2&tag=nrjc-21&linkId=f0dfb66dafcb0c6e9449e7b1a4ae1ac215 ''Gears, page 57, GCSE Physics; The Revision Guide, CGP, AQA '']
 +
:[https://www.amazon.co.uk/gp/product/019835939X/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=019835939X&linkCode=as2&tag=nrjc-21&linkId=57e96876985fc39b1a3d8a3e3dc238b6 ''Gears, pages 122-123, GCSE Physics; Third Edition, Oxford University Press, AQA '']
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====Edexcel====
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:[https://www.amazon.co.uk/gp/product/1292120223/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1292120223&linkCode=as2&tag=nrjc-21&linkId=068ecf40278c32406a7f1c6e66751417 ''Gears, page 137, GCSE Physics, Pearson Edexcel '']
 +
:[https://www.amazon.co.uk/gp/product/1782948163/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782948163&linkCode=as2&tag=nrjc-21&linkId=0fdbfd5dd397d6e24a9dfb250f08587f ''Gears, page 213, GCSE Physics, CGP, Edexcel '']
 +
:[https://www.amazon.co.uk/gp/product/1782945733/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945733&linkCode=as2&tag=nrjc-21&linkId=2a2dbec9db6bf5766c0458d908fa0a52 ''Gears, page 69, GCSE Physics; The Revision Guide, CGP, Edexcel '']
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====OCR====
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:[https://www.amazon.co.uk/gp/product/1782945687/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945687&linkCode=as2&tag=nrjc-21&linkId=9a598e52189317a20311d7a632747bc9 ''Gears, page 39, Gateway GCSE Physics; The Revision Guide, CGP, OCR  '']
 +
:[https://www.amazon.co.uk/gp/product/0198359837/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=0198359837&linkCode=as2&tag=nrjc-21&linkId=3c4229e8b023b2b60768e7ea2307cc6f ''Gears, pages 87, Gateway GCSE Physics, Oxford, OCR '']

Latest revision as of 11:38, 11 December 2019

Key Stage 2

Meaning

You can change the gears on a bicycle to make it easier to go up a hill.

Gears are circular disks with 'teeth' that lock together with other gears to change how quickly they spin.

About Gears

Gears are used in bikes, cars, and any engine which turns.
Gear2.png
The speed can be made bigger by turning the larger gear. The small gear will turn more quickly.

Key Stage 3

Meaning

Gears are circular disks with 'teeth' that can act to increase the speed or the moment of a force.

About Gears

A small gear turning a large gear acts to decrease the speed and increase the moment.
A large gear turning a small gear acts to increase the speed and decrease the moment.

Key Stage 4

Meaning

Gears are circular disks with 'teeth' that can act to increase the speed or the moment of a force.

About Gears

The multiplying effect of gears can be found by the ratio of the radii or the number of 'teeth'.
A gear with few teeth turning a gear with many teeth acts to decrease the speed and increase the moment.
A gear with many teeth turning a gear few teeth acts to increase the speed and decrease the moment.
The force on one gear is equal in magnitude to the force applied to the other gear.

Example Calculations

A gear with radius 50mm is turned with a moment of 10Nm. This gear used to turn a second gear with a radius of 20mm. Calculate the moment of the second gear. A gear with 45 teeth is turned with a moment of 25Nm. This gear used to turn a second gear with a 63 teeth. Calculate the moment of the second gear. A gear with 144 teeth is turned with a moment of 72Nm. This gear used to turn a second gear with 60 teeth. Calculate the moment of the second gear.
1. State the known quantities

Moment = 10N

Radius 1 = 50mm = 0.05m

Radius 2 = 20mm = 0.02m

1. State the known quantities

Moment = 25Nm

Teeth Ratio = 45:63

1. State the known quantities

Moment = 70Nm

Teeth Ratio = 144:60

2. Substitute the numbers into the equation and solve.

\(M = Fd\)

\( 10 = F \times 0.05\)

\( F = 200N\)

An equal force applies to the second gear.

\( M = F \times d\)

\( M = 200 \times 0.02\)

\( M = 4Nm\)

2. Substitute the numbers into the equation and solve.

\( M = \frac {25}{45} \times 63\)

\( M = 35Nm\)

2. Substitute the numbers into the equation and solve.

\( M = \frac {72}{144} \times 60\)

\( M = 30Nm\)

References

AQA

Gears, page 133, GCSE Physics, Hodder, AQA
Gears, page 167, GCSE Physics; The Complete 9-1 Course for AQA, CGP, AQA
Gears, page 171, GCSE Physics; Student Book, Collins, AQA
Gears, page 57, GCSE Physics; The Revision Guide, CGP, AQA
Gears, pages 122-123, GCSE Physics; Third Edition, Oxford University Press, AQA

Edexcel

Gears, page 137, GCSE Physics, Pearson Edexcel
Gears, page 213, GCSE Physics, CGP, Edexcel
Gears, page 69, GCSE Physics; The Revision Guide, CGP, Edexcel

OCR

Gears, page 39, Gateway GCSE Physics; The Revision Guide, CGP, OCR
Gears, pages 87, Gateway GCSE Physics, Oxford, OCR
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