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Force/Lesson on Force: Difference between revisions
From OER in Education
→The distinction between ‘power’ and ‘energy’
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== The distinction between ‘power’ and ‘energy’ == | == The distinction between ‘power’ and ‘energy’ == | ||
<center>The distinction between ‘power’ and ‘energy’</center> | |||
|- | |||
| style="border-top:0.5pt solid #000000;border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-right:none;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| <center>[[Image:]]</center> | |||
| style="border:0.5pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| 10s | |||
100 m | |||
|- | |||
| style="border-top:0.5pt solid #000000;border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-right:none;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| 30n | |||
| style="border:0.5pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Energy: 30n x 100m = 3000jPower: 3000j/10s = 300j/s | |||
|- | |||
| style="border-top:0.5pt solid #000000;border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-right:none;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| <center>[[Image:]]</center> | |||
| style="border:0.5pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| 1000s | |||
100 m | |||
|- | |||
| style="border-top:0.5pt solid #000000;border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-right:none;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| 30n | |||
| style="border:0.5pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Energy: 30n x 100m = 3000j | |||
Power: 3000j/1000s = 3j/s | |||
|} | |||
The important thing to stress is that in both cases, the ‘work done’ or ENERGY is the same – it being the product of the force (weight of the animal) measured in Newtons, and the distance travelled, measured in meters – regardless of speed. The units for ENERGY are Joules. | |||
POWER is the ''rate'' at which the ENERGY is converted. This is measured in Joules per second (Watts). | |||
{| style="border-spacing:0;" | |||
| colspan="2" style="border:0.5pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| <center>'''Representing Forces'''</center> | |||
|- | |||
| style="border-top:0.5pt solid #000000;border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-right:none;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| <center>'''Drawing Demand'''</center> | |||
| style="border:0.5pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| <center>'''Conceptual Demand'''</center> | |||
|- | |||
| style="border-top:0.5pt solid #000000;border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-right:none;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| <center>Single Arrow</center> | |||
| style="border:0.5pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| <center>Single Arrow</center> | |||
|- | |||
| style="border-top:0.5pt solid #000000;border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-right:none;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| <center>Direction of arrow</center> | |||
| style="border:0.5pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| <center>Force has direction</center> | |||
|- | |||
| style="border-top:0.5pt solid #000000;border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-right:none;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| <center>Straightness of arrow</center> | |||
| style="border:0.5pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| <center>Forces act in straight lines</center> | |||
|- | |||
| style="border-top:0.5pt solid #000000;border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-right:none;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| | |||
| style="border:0.5pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| | |||
|- | |||
| style="border-top:0.5pt solid #000000;border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-right:none;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| <center>Length of arrow</center> | |||
| style="border:0.5pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| <center>Magnitude of force</center> | |||
|- | |||
| style="border-top:0.5pt solid #000000;border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-right:none;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| <center>Location of arrow’s tail</center> | |||
| style="border:0.5pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| <center>Objects as point masses</center> | |||
|} | |||
{| style="border-spacing:0;" | |||
| style="border-top:0.5pt solid #000000;border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-right:none;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| <center>'''Two Arrows'''</center> | |||
| style="border:0.5pt solid #000000;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| <center>'''Two Arrows'''</center> | |||
|- | |||
| style="border-top:0.5pt solid #000000;border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-right:none;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;" | |||
The important thing to stress is that in both cases, the ‘work done’ or ENERGY is the same – it being the product of the force (weight of the animal) measured in Newtons, and the distance travelled, measured in meters – regardless of speed. The units for ENERGY are Joules. | The important thing to stress is that in both cases, the ‘work done’ or ENERGY is the same – it being the product of the force (weight of the animal) measured in Newtons, and the distance travelled, measured in meters – regardless of speed. The units for ENERGY are Joules. | ||
