Cours de méthodologie en physique (bilingue : français/anglais) bâti pour l'Ecole d'été de l'Institut de Technologie du Cambodge, Autour de la thermodynamique

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Ce module présente un cours de méthodologie en physique : (1) Incertitudes et analyse dimensionnelle (2) Autour de l'oscillateur harmonique (3) Autour de la thermodynamique (4) Autour de l'optique géométrique et ondulatoire

Publié le : dimanche 1 janvier 2012
Lecture(s) : 70
Licence : En savoir +
Paternité, pas d'utilisation commerciale, partage des conditions initiales à l'identique
Nombre de pages : 35
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Autour de la thermodynamique

About « Thermodynamics »

Cours de méthodologie – Ecole d’été (ITC Phnom Penh)

Olivier GRANIER

(Du lundi 20 au mercredi 29 août 2012)

1

1) Some experimental setups about phase transitions :
A phase transition is the transformation of
a thermodynamic system from one phase or
state of matter to another.

→
Φ Φ
1 2

←

Latent heat of phase transition :

q = l = h − h =Δh
m 1→2,m 2,m 1,m m


ΔH = ml = Q
1→2,m


ml
Q
1→2,m
ΔS = =

T T


ΔU = ml − Pm( v − v )

1→2,m 2,m 1,m
2



A few cubic centimeters of water is poured into a can (just enough to cover the bottom).

The can is held above a laboratory burner for about 30 seconds, the water can be
brought to the boiling point where its vapor pressure is equal to atmospheric pressure.

The vapor will then push most of the air out of the can.
3

Videos : « Crushing of Steel Drum – DRUM4 »
« Can-Crushing Experiment – CRUSHCAN »


If the can is quickly inverted into a beaker of water, sealing off the opening,
the sudden drop in vapor pressure will result in enough net inward pressure
to quickly crush the can.
4

Vidéo : « Le bouillant de Franklin »
Wet towel
Boiling water
Bubbles
Steam
(Boiling water again)
Water
Laboratory burner



5


Phase changes (for water, under P = 1 bar) from ice to steam.
The energies required to accomplish the phase changes (called the latent heat of fusion
and latent heat of vaporization ) would lead to plateaus in the temperature vs time
graph.
6

Phase diagram

7

Vidéo : « Going around the critical point »
Enceinte thermostatique (Insulated cylinder)
Volant (Steering wheel)

8

Vidéo : « Going around the critical point »

In any system containing liquid and gaseous
phases, there exists a special combination of
pressure and temperature, known as the
critical point.

Near the critical point, the fluid is
sufficiently hot and compressed that the
distinction between the liquid and gaseous
phases is almost non-existent.

This is associated with the phenomenon of
critical opalescence, a milky appearance of
the liquid due to density fluctuations at all
possible wavelengths
(including those of visible light).

9


Thermostat at T
(Temperature being kept constant)
Water and a
Seam water and Saturated steam
Water
Steam water
steam bubble
a drop of water and water
Isothermal
Isothermal
Dew point
Phase transition Boiling point
compression of
compression of
(Condensation)
water
steam

10

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