Thermodynamical asymmetries in whirling, jumping and walking

Güémez, J.; Fiolhais, M.

doi:10.1088/0143-0807/35/3/035008

Cited by 7 publications

(20 citation statements)

References 21 publications

(30 reference statements)

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“…In a recent publication we discuss the same type of asymmetries in the context of human movements, like jumping and walking [17]. As in the example discussed in this paper, in one part of the process there is a direct conversion of internal energy into mechanical energy but, in the other part, the mechanical energy dissipates as heat in the surroundings.…”

Section: Energetic Issuesmentioning

confidence: 77%

The physics of articulated toys—a jumping and rotating kangaroo

Güémez¹,

Fiolhais²

2014

Eur. J. Phys.

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We describe the physics of an articulated toy with an internal source of energy provided by a spiral spring. The toy is a funny low cost kangaroo which jumps and rotates. The study consists of a mechanical and a thermodynamical analysis which makes use of the Newton and center of mass equations, the rotational equations and the first law of thermodynamics. This amazing toy provides a nice demonstrative example how new physics insights can be brought about when links with thermodynamics are established in the study of mechanical systems.

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Section: Energetic Issuesmentioning

confidence: 77%

The physics of articulated toys—a jumping and rotating kangaroo

Güémez¹,

Fiolhais²

2014

Eur. J. Phys.

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“…The force F acts during the time interval ∆t, and the car accelerates from the initial velocity v i = 0 to the final one v f = V cm , traveling a distance ∆X cm . The Newton's second law expressed by (12) and by the centre-of-mass equation (13) lead, respectively to…”

Section: The Motion Of An Accelerated Carmentioning

confidence: 99%

“…at the base of the incline (zero initial velocity is assumed) and the distance ∆X cm was traveled in the time interval ∆t. The centre-of-mass equation (13) leads to…”

Section: Sliding and Rotating Disc In A Slippery Slopementioning

confidence: 99%

Dissipation effects in mechanics and thermodynamics

Güémez¹,

Fiolhais²

2016

Eur. J. Phys.

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With the discussion of three examples, we aim at clarifying the concept of energy transfer associated with dissipation in mechanics and in thermodynamics. The dissipation effects due to dissipative forces, such as the friction force between solids or the drag force in motions in fluids , lead to an internal energy increase of the system and/or to a heat transfer to the surrounding. This heat flow is consistent with the second law, which states that the entropy of the universe should increase when those forces are present because of the irreversibility always associated with their actions. As far as mechanics is concerned the effects of the dissipative forces are include in the Newton's equations as impulses and pseudo-works.

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“…In a recent publication [5] we studied the energy transfers in various human movements such as whirling, jumping and walking. The arguments presented in [5] also apply here. The motion is possible because Marta possesses an internal source of energy.…”

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confidence: 99%

“…The conclusion is clear: the internal energy provided by Marta is transferred as heat to the surrounding where it is dissipated, and the global process leads to an entropy increase of the universe [3,5,6]. Certainly, part of this energy can also be reabsorbed by Marta but this energy degradates, in the sense that it will not be useful anymore (for, instance, the temperature of Marta may slightly increase).…”

mentioning

confidence: 99%