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Kinetic Energy Store

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==Key Stage 3==
===Meaning===
[[File:CarMoving.gif|right|300px|thumb|The car has [[energy]] in its '''kinetic energy store'''.]]
The '''kinetic energy store''' is the [[Energy Store|energy store]] associated with moving [[object]]s.
|[[File:KineticEnergyEquation.png|center|500px]]
|-
| style="height:20px; width:500px; text-align:center;" |TextThe equation for '''kinetic energy''' written in words.
|}
|[[File:KineticEnergySymbolEquation.png|center|400px]]
|-
| style="height:20px; width:400px; text-align:center;" |TextThe equation for '''kinetic energy''' written in symbols.
|}
 
===Calculating Kinetic Energy===
{| class="wikitable"
| style="height:20px; width:200px; text-align:center;" |A 700kg formula one racing car has a top speed of 100m/s. Calculate the '''kinetic energy''' of the [[car]] to two [[Significant Figures|significant figures]].
 
| style="height:20px; width:200px; text-align:center;" |A cheetah of mass 75kg runs at a speed of 32m/s. Calculate the '''kinetic energy''' of the cheetah correct to two [[Significant Figures|significant figures]].
 
| style="height:20px; width:200px; text-align:center;" |A 160g cricket ball is hit at 44m/s. Calculate the '''kinetic energy''' of the cricket ball correct to two [[Significant Figures|significant figures]].
 
|-
| style="height:20px; width:200px; text-align:left;" |'''1. State the known quantities'''
 
m = 700kg
 
v = 100m/s
| style="height:20px; width:200px; text-align:left;" |'''1. State the known quantities'''
 
m = 75kg
 
v = 32m/s
| style="height:20px; width:200px; text-align:left;" |'''1. State the known quantities'''
m = 160g
 
'''Convert [[mass]] into [[kilogram]]s.'''
 
m<sub>in kilograms</sub> = <math>\frac{160}{1000}</math>
 
m = 0.16kg
 
v = 32m/s
 
|-
| style="height:20px; width:200px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and [[Solve (Maths)|solve]].'''
 
<math>E_k = \frac{1}{2} m v^2</math>
 
<math>E_k = \frac{1}{2} \times 700 \times 100^2</math>
 
<math>E_k = \frac{1}{2} \times 700 \times 10,000</math>
 
<math>E_k = 3,500,000J</math>
 
| style="height:20px; width:200px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and [[Solve (Maths)|solve]].'''
 
<math>E_k = \frac{1}{2} m v^2</math>
 
<math>E_k = \frac{1}{2} \times 75 \times 32^2</math>
 
<math>E_k = \frac{1}{2} \times 75 \times 1024</math>
 
<math>E_k = 38,400J</math>
 
<math>E_k \approx 38000J</math>
| style="height:20px; width:200px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and [[Solve (Maths)|solve]].'''
 
<math>E_k = \frac{1}{2} m v^2</math>
 
<math>E_k = \frac{1}{2} \times m \times v^2</math>
 
<math>E_k = \frac{1}{2} \times 0.16 \times 44^2</math>
 
<math>E_k = \frac{1}{2} \times 0.16 \times 1936</math>
 
<math>E_k = 154.88J</math>
 
<math>E_k \approx 150J</math>
 
|}
 
==Key Stage 4==
{{#ev:youtube|https://www.youtube.com/watch?v=6hOVedwiNh0}}
===Meaning===
The '''kinetic energy store''' is the [[Energy Store|energy store]] associated with moving [[object]]s.
 
===About Kinetic Energy===
: Any moving [[object]] stores '''kinetic energy'''.
: The '''kinetic energy store''' of an [[object]] is related to two [[property|properties]] of the [[object]]:
*The [[mass]] of the [[object]] - The greater the [[mass]] the greater the '''kinetic energy''' stored.
*The [[speed]] or [[velocity]] of the [[object]] - The greater the [[speed]] the greater the '''kinetic energy''' stored.
 
===Equation===
''NB: You must memorise this equation!''
 
'' '''Kinetic Energy''' = 0.5 x (Mass) x (Speed)<sup>2</sup>''
 
<math>E_k = \frac{1}{2} m v^2</math>
 
Where:
 
E<sub>k</sub> = '''Kinetic Energy''' stored.
 
m = The [[mass]] of the [[object]].
 
v = The [[speed]] or [[velocity]] of the [[object]].
 
===Calculating Kinetic Energy===
{{#ev:youtube|https://www.youtube.com/watch?v=D-eCSsnFEy0}}
 
{| class="wikitable"
| style="height:20px; width:200px; text-align:center;" |A 700kg formula one racing car has a top speed of 100m/s. Calculate the '''kinetic energy''' of the [[car]] to two [[Significant Figures|significant figures]].
 
| style="height:20px; width:200px; text-align:center;" |A cheetah of mass 75kg runs at a speed of 32m/s. Calculate the '''kinetic energy''' of the cheetah correct to two [[Significant Figures|significant figures]].
 
| style="height:20px; width:200px; text-align:center;" |A 160g cricket ball is hit at 44m/s. Calculate the '''kinetic energy''' of the cricket ball correct to two [[Significant Figures|significant figures]].
 
|-
| style="height:20px; width:200px; text-align:left;" |'''1. State the known quantities'''
 
m = 700kg
 
v = 100m/s
| style="height:20px; width:200px; text-align:left;" |'''1. State the known quantities'''
 
m = 75kg
 
v = 32m/s
| style="height:20px; width:200px; text-align:left;" |'''1. State the known quantities'''
m = 160g
 
'''Convert [[mass]] into [[kilogram]]s.'''
 
m<sub>in kilograms</sub> = <math>\frac{160}{1000}</math>
 
m = 0.16kg
 
v = 32m/s
 
|-
| style="height:20px; width:200px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and [[Solve (Maths)|solve]].'''
 
<math>E_k = \frac{1}{2} m v^2</math>
 
<math>E_k = \frac{1}{2} \times 700 \times 100^2</math>
 
<math>E_k = \frac{1}{2} \times 700 \times 10,000</math>
 
<math>E_k = 3,500,000J</math>
 
| style="height:20px; width:200px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and [[Solve (Maths)|solve]].'''
 
<math>E_k = \frac{1}{2} m v^2</math>
 
<math>E_k = \frac{1}{2} \times 75 \times 32^2</math>
 
<math>E_k = \frac{1}{2} \times 75 \times 1024</math>
 
<math>E_k = 38,400J</math>
 
<math>E_k \approx 38000J</math>
| style="height:20px; width:200px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and [[Solve (Maths)|solve]].'''
 
<math>E_k = \frac{1}{2} m v^2</math>
 
<math>E_k = \frac{1}{2} \times m \times v^2</math>
 
<math>E_k = \frac{1}{2} \times 0.16 \times 44^2</math>
 
<math>E_k = \frac{1}{2} \times 0.16 \times 1936</math>
 
<math>E_k = 154.88J</math>
 
<math>E_k \approx 150J</math>
|}
 
===Calculating Velocity from Kinetic Energy===
{| class="wikitable"
| style="height:20px; width:200px; text-align:center;" |A 75kg person has a '''kinetic energy''' of 96J while while walking. Calculate their [[speed]].
| style="height:20px; width:200px; text-align:center;" |A [[bird]] of [[mass]] 2.4kg flies at a constant [[speed]] with a '''kinetic energy store''' of 1500J. Calculate the [[speed]] of the [[bird]] correct to two [[Significant Figure|significant figures]].
| style="height:20px; width:200px; text-align:center;" |A 60g bullet has a '''kinetic energy store''' of 750J. Calculate the [[speed]] of the bullet correct to two [[Significant Figures|significant figures]].
|-
| style="height:20px; width:200px; text-align:left;" |'''1. State the known quantities'''
E<sub>k</sub> = 96J
 
m = 75kg
| style="height:20px; width:200px; text-align:left;" |'''1. State the known quantities'''
E<sub>k</sub> = 1500J
 
m = 2.4kg
| style="height:20px; width:200px; text-align:left;" |'''1. State the known quantities'''
E<sub>k</sub> = 750J
 
m = 60g = 0.06kg
|-
| style="height:20px; width:200px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers and [[Evaluate (Maths)|evaluate]].'''
 
<math>E_k = \frac{1}{2} m v^2</math>
 
<math>96 = \frac{1}{2} \times 75 \times v^2</math>
 
<math>96 = 37.5v^2</math>
 
| style="height:20px; width:200px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers and [[Evaluate (Maths)|evaluate]].'''
<math>E_k = \frac{1}{2} m v^2</math>
 
<math>1500 = \frac{1}{2} \times 2.4 \times v^2</math>
 
<math>1500 = 1.2v^2</math>
| style="height:20px; width:200px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers and [[Evaluate (Maths)|evaluate]].'''
<math>E_k = \frac{1}{2} m v^2</math>
 
<math>750 = \frac{1}{2} \times 0.06 \times v^2</math>
 
<math>750 = 0.03v^2</math>
|-
| style="height:20px; width:200px; text-align:left;" |'''3. [[Rearrange (Maths)|Rearrange]] the equation and [[Solve (Maths)|solve]].'''
 
<math>v^2 = \frac{96}{37.5}</math>
 
<math>v = \sqrt{\frac{96}{37.5}}</math>
 
<math>v = 1.6m/s</math>
 
| style="height:20px; width:200px; text-align:left;" |'''3. [[Rearrange (Maths)|Rearrange]] the equation and [[Solve (Maths)|solve]].'''
 
<math>v^2 = \frac{1500}{1.2}</math>
 
<math>v = \sqrt{\frac{1500}{1.2}}</math>
 
<math>v = 35.35534m/s</math>
 
<math>v \approx 35m/s</math>
 
| style="height:20px; width:200px; text-align:left;" |'''3. [[Rearrange (Maths)|Rearrange]] the equation and [[Solve (Maths)|solve]].'''
 
<math>v^2 = \frac{750}{0.06}</math>
 
<math>v = \sqrt{\frac{750}{0.06}}</math>
 
<math>v = 158.1139m/s</math>
 
<math>v \approx 160m/s</math>
|}
 
===References===
====AQA====
 
:[https://www.amazon.co.uk/gp/product/1782945598/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945598&linkCode=as2&tag=nrjc-21&linkId=ad276ad49df77ab4b40ab4fd0fe10021 ''Kinetic energy stores, page 169, GCSE Combined Science; The Revision Guide, CGP, 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=f0dfb66dafcb0c6e9449e7b1a4ae1ac270 ''Kinetic energy stores, pages 11, 15, GCSE Physics; The Revision Guide, CGP, AQA '']
:[https://www.amazon.co.uk/gp/product/1782946403/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782946403&linkCode=as2&tag=nrjc-21&linkId=32a0abb60dff015b15b50e9b1d7b4644 ''Kinetic energy stores, pages 21, 25, 27, 30, GCSE Combined Science Trilogy; Physics, CGP, AQA '']
:[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 ''Kinetic energy stores, pages 22, 26, 28, 31, GCSE Physics; The Complete 9-1 Course for AQA, CGP, AQA '']
:[https://www.amazon.co.uk/gp/product/1782946403/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782946403&linkCode=as2&tag=nrjc-21&linkId=32a0abb60dff015b15b50e9b1d7b4644 ''Kinetic energy stores; of particles, pages 34, 100, 104, GCSE Combined Science Trilogy; Physics, CGP, AQA '']
:[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 ''Kinetic energy stores; of particles, pages 35, 110, 114, GCSE Physics; The Complete 9-1 Course for AQA, CGP, AQA '']
 
====Edexcel====
 
:[https://www.amazon.co.uk/gp/product/1292120193/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1292120193&linkCode=as2&tag=nrjc-21&linkId=572df39392fb4200db8391d98ae6314e ''Kinetic energy (KE), pages 316, 323, GCSE Combined Science, Pearson Edexcel '']
:[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 ''Kinetic energy (KE), pages 34, 41, 156, 192, 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 ''Kinetic energy stores, pages 61, 66, 200, GCSE Physics, CGP, Edexcel '']
 
====OCR====
:[https://www.amazon.co.uk/gp/product/1782945695/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945695&linkCode=as2&tag=nrjc-21&linkId=ceafcc80bcad6b6754ee97a0c7ceea53 ''Kinetic energy stores, page 167, 202, 206, Gateway GCSE Combined Science; The Revision Guide, CGP, OCR '']
:[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 ''Kinetic energy stores, pages 14, 32, 34, 82, 86, 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 ''Kinetic energy/store, pages 58-59, 192, 194-199, 285, Gateway GCSE Physics, Oxford, OCR '']
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