Name: gravitational and elastic energy stored
Uploaded: 2023-09-22T11:49:37.000Z
Duration: 1 min 9 s
Channel: JoVE

L’énergie potentielle est la capacité d’un corps à travailler en raison de sa position.
La variation d’énergie potentielle gravitationnelle est la négative du travail effectué sur un corps par une force, égale et opposée à son poids, pour amener le corps à une position spécifique à partir d’une position de référence ou d’une donnée où l’énergie potentielle gravitationnelle est considérée comme nulle.
Lors du soulèvement d’un corps, le travail effectué par la force gravitationnelle est négatif, et donc son énergie potentielle augmente. En déplaçant le corps vers le bas, l’inverse est observé.
L’énergie potentielle élastique est le négatif du travail effectué en raison de la force de rappel générée dans un corps élastique déformé qui tente de restaurer sa position non déformée.
Pour un ressort comprimé, la variation de l’énergie potentielle élastique est positive, tandis que le travail effectué par la force du ressort sur la masse est négatif. La même chose est observée lorsque le ressort est étiré à partir d’une position non déformée.
Si les forces gravitationnelles et élastiques agissent toutes deux sur un corps, l’énergie potentielle est la somme des deux énergies.

<ol>
	<li>Hibbeler, R.C. (2016). Mécanique du génie : Statique. Quatorzième édition, New Jersey : Pearson. Pages 598 et 599.</li>
	<li>Meriam, J.L., Kraige, L.G. et Bolten, J.N. (2016). Mécanique de l’ingénierie : statique et dynamique. Huitième édition, Singapour : John Wiley & Sons. P. 411 à 413.</li>
</ol>

Énergie potentielle

Potential Energy

Une force conservative, comme une force gravitationnelle ou élastique, donne au corps la capacité de faire du travail. Cette capacité, mesurée sous forme d'énergie potentielle, dépend de la "position" du corps par rapport à une position de référence fixe. L'énergie potentielle gravitationnelle est considérée comme nulle au point de référence. Supposons qu'un corps se trouve à une certaine distance verticale au-dessus d'un référentiel horizontal fixe. Dans ce cas, le poids du corps a une énergie potentielle gravitationnelle positive, car il a la capacité d'effectuer un travail positif lorsque le corps est ramené vers le référentiel. De même, si le corps se trouve à une distance verticale en-dessous du référentiel, l'énergie potentielle gravitationnelle est négative car le poids effectue un travail négatif lorsque le corps est ramené vers le référentiel. Si la hauteur est prise comme étant zéro par rapport au référentiel et que la distance verticale vers le haut est considérée comme positive, alors à une certaine hauteur au-dessus du plan de référence, l'énergie potentielle gravitationnelle est exprimée comme le produit du poids du corps et de sa hauteur par rapport au plan de référence. Mathématiquement, cela s'exprime comme suit : <img alt="Equation 1" src="/files/ftp_upload/14358/PT_14358_Equation_1.svg" style="text-align: center; height: 15px;"> Si le corps se trouve à une certaine distance en-dessous du plan de référence, son énergie potentielle gravitationnelle devient négative. Remarquez que le plan de référence pour l'énergie potentielle zéro est arbitraire car il n'affecte pas le changement d'énergie potentielle. Le travail effectué sur un corps élastique est stocké dans le corps sous forme d'énergie potentielle élastique. Cette énergie est disponible pour effectuer un travail sur un autre corps tout en soulageant sa compression ou son extension. Lorsqu'une force compresse un ressort, elle provoque un déplacement x, qui est directement proportionnel à la force appliquée. L'énergie potentielle élastique du ressort pour une compression de x est le travail total effectué sur le ressort et est exprimé comme suit : <img alt="Equation 1" src="/files/ftp_upload/14358/PT_14358_Equation_2.svg" style="text-align: center; height: 30px;"> Lorsqu'un ressort est étiré, la force agit dans la direction du déplacement, effectuant ainsi un travail positif sur le ressort et augmentant son énergie potentielle. Il en va de même lorsqu'un ressort est comprimé à partir d'une position non déformée.

Une force conservatrice, telle qu’une force gravitationnelle ou élastique, donne au corps la capacité de travailler. Cette capacité, mesurée comme l’énergie potentielle, ...

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gravitational and elastic energy stored

Gravitational and elastic potential energy are forms of stored energy from conservative forces. A conservative force, such as gravity or an elastic force, gives a body the capacity to do work. This capacity is measured as potential energy and depends on the body’s position relative to a fixed reference point, or datum.

For gravitational potential energy, the datum is the level where the energy is taken as zero. If a body is above this reference plane, its weight has positive gravitational potential energy because it can do positive work as the body moves back down to the datum. If the body is below the datum, the gravitational potential energy is negative because the weight does negative work as the body is moved up to the reference level.

If height is measured upward from the datum as positive and zero is set at the reference plane, gravitational potential energy equals the body’s weight multiplied by its height. If the body is below the datum plane, the value becomes negative. The choice of zero potential energy is arbitrary, because only the change in potential energy matters.

Elastic potential energy is stored when work is done on an elastic body, such as a spring. This stored energy can later do work on another body as the spring returns toward its original shape. When a force compresses a spring, it produces a displacement x that is directly proportional to the applied force, and the elastic potential energy is the total work done on the spring.

A stretched spring also gains elastic potential energy because the force acts in the same direction as the displacement and does positive work on the spring. The same increase in potential energy is seen when a spring is compressed from its undeformed position.

Gravitational and Elastic Energy Stored

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Explore how gravity and springs store energy as potential energy, including positive and negative gravitational values and elastic energy in stretched or compressed springs.

Gravitational and Elastic Energy Stored | JoVE K12

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Gravitational and Elastic Energy Stored

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