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

A energia potencial é a capacidade de um corpo de fazer o trabalho devido à sua posição.
A mudança de energia potencial gravitacional é o negativo do trabalho realizado em um corpo pela força, igual e oposta ao seu peso, ao trazer o corpo para uma posição específica a partir de uma posição de referência ou dado onde a energia potencial gravitacional é considerada zero.
Ao levantar um corpo, o trabalho realizado pela força gravitacional é negativo e, portanto, sua energia potencial aumenta. Ao mover o corpo para baixo, observa-se o inverso.
A energia potencial elástica é o negativo do trabalho realizado devido à força restauradora gerada em um corpo elástico deformado que tenta restaurar sua posição não deformada.
Para uma mola comprimida, a mudança na energia potencial elástica é positiva, enquanto o trabalho realizado pela força da mola na massa é negativo. O mesmo é observado quando a mola é esticada de uma posição não deformada.
Se as forças gravitacionais e elásticas atuam sobre um corpo, a energia potencial é a soma de ambas as energias.

<ol>
	<li>Hibbeler, R.C. (2016). Engenharia Mecânica: Estática. Décima quarta edição, Nova Jersey: Pearson. Pág. 598-599.</li>
	<li>Meriam, J.L., Kraige, L.G. e Bolten, J.N.(2016). Engenharia Mecânica: Estática e Dinâmica. Oitava Edição, Cingapura: John Wiley & Sons. Pág. 411-413.</li>
</ol>

energia potencial

Potential Energy

Uma força conservativa, como a força gravitacional ou elástica, dá ao corpo a capacidade de realizar trabalho. Essa capacidade, medida como energia potencial, depende da posição' ou “deslocamento“ do corpo em relação a uma posição de referência fixa ou plano de referência. A energia potencial gravitacional é considerada zero no ponto de referência. Suponha que um corpo esteja localizado a alguma distância vertical acima de um plano de referência horizontal fixo ou datum. Nesse caso, o peso do corpo possui energia potencial gravitacional positiva, pois possui a capacidade de realizar trabalho positivo quando o corpo é movido de volta ao datum.

Da mesma forma, se o corpo estiver localizado a uma distância vertical abaixo do datum, a energia potencial gravitacional é negativa, pois o peso realiza trabalho negativo quando o corpo é movido de volta ao datum.

Se a altura for considerada zero no datum e a distância vertical ascendente for considerada positiva, então em alguma altura acima do plano datum, a energia potencial gravitacional é expressa como o produto do peso do corpo e sua altura em relação ao plano datum. Matematicamente, isso é expresso da seguinte forma:

<img alt="Equation 1" src="/files/ftp_upload/14358/PT_14358_Equation_1.svg" style="text-align: center; height: 15px;" />

Se o corpo estiver a alguma distância abaixo do plano datum, sua energia potencial gravitacional se torna negativa. Note que o plano datum para energia potencial zero é arbitrário, pois não afeta a alteração na energia potencial.

O trabalho realizado em um corpo elástico é armazenado no corpo na forma de energia potencial elástica. Essa energia está disponível para realizar trabalho em outro corpo ao aliviar sua compressão ou expansão. Quando uma força comprime uma mola, ela causa um deslocamento x, que é diretamente proporcional à força aplicada. A energia potencial elástica da mola para uma compressão de x é o trabalho total realizado na mola e é expressa da seguinte forma:

<img alt="Equation 1" src="/files/ftp_upload/14358/PT_14358_Equation_2.svg" style="text-align: center; height: 30px;" />

Quando uma mola é esticada, a força atua na direção do deslocamento, realizando trabalho positivo na mola e aumentando sua energia potencial. O mesmo é observado quando uma mola é comprimida a partir de uma posição não deformada.

Energia Potencial

Uma força conservativa, como uma força gravitacional ou elástica, dá ao corpo a capacidade de trabalhar. Essa capacidade, medida como a energia potencial, ...

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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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Gravitational and Elastic Energy Stored

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