Difference between revisions of "Kinetic Energy Store"
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| style="height:20px; width:400px; text-align:center;" |The equation for '''kinetic energy''' written in symbols. | | style="height:20px; width:400px; text-align:center;" |The 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.''' | ||
| + | |||
| + | <math>m = \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== | ||
| + | ===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=== | ||
Revision as of 12:16, 31 January 2019
Contents
Key Stage 3
Meaning
The car has energy in its kinetic energy store.
The kinetic energy store is the energy store associated with moving objects.
About The Kinetic Energy Store
- The faster an object moves the more energy it has in its kinetic store.
- If two objects are moving at the same speed the one with more mass has more energy in the kinetic store.
Equation
 |
| The equation for kinetic energy written in words. |
 |
| The equation for kinetic energy written in symbols. |
Calculating Kinetic Energy
| A 700kg formula one racing car has a top speed of 100m/s. Calculate the kinetic energy of the car to two significant figures. | A cheetah of mass 75kg runs at a speed of 32m/s. Calculate the kinetic energy of the cheetah correct to two significant figures. | A 160g cricket ball is hit at 44m/s. Calculate the kinetic energy of the cricket ball correct to two significant figures. |
| 1. State the known quantities
m = 700kg v = 100m/s |
1. State the known quantities
m = 75kg v = 32m/s |
1. State the known quantities
m = 160g \(m = \frac{160}{1000}\) m = 0.16kg v = 32m/s |
| 2. Substitute the numbers into the equation and solve.
\(E_k = \frac{1}{2} m v^2\) \(E_k = \frac{1}{2} \times 700 \times 100^2\) \(E_k = \frac{1}{2} \times 700 \times 10,000\) \(E_k = 3,500,000J\) |
2. Substitute the numbers into the equation and solve.
\(E_k = \frac{1}{2} m v^2\) \(E_k = \frac{1}{2} \times 75 \times 32^2\) \(E_k = \frac{1}{2} \times 75 \times 1024\) \(E_k = 38,400J\) \(E_k \approx 38000J\) |
2. Substitute the numbers into the equation and solve.
\(E_k = \frac{1}{2} m v^2\) \(E_k = \frac{1}{2} \times m \times v^2\) \(E_k = \frac{1}{2} \times 0.16 \times 44^2\) \(E_k = \frac{1}{2} \times 0.16 \times 1936\) \(E_k = 154.88J\) \(E_k \approx 150J\) |
Key Stage 4
Meaning
The kinetic energy store is the energy store associated with moving objects.
About Kinetic Energy
- Any moving object stores kinetic energy.
- The kinetic energy store of an object is related to two 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)2
\(E_k = \frac{1}{2} m v^2\)
Where:
Ek = Kinetic Energy stored.
v = The speed or velocity of the object.