Physik

21.471 Beiträge
Wärmekapazität und latente Wärme?

Die Zeit läuft davon...

Aufgabe:

"In einem Glas befinden sich 0.5 Liter Wasser bei einer Temperatur von T2 = 20◦C. a) Wieviel Wärme muss dem Wasser entzogen werden, um es auf die Temperatur T1 = 5◦C abzukühlen?
Hinweis für flüßiges Wasser beträgt die spezifische Wärmekapazität c_Wasser = 4.2 Jg−1K−1 . Die Dichte beträgt ρWasser = 1.0 cm−3 .

(b) In das Wasserglas aus (a) bei der Temperatur T2 = 20◦C wird ein Eiswurfel der ¨ Temperatur T0 = −18◦C gegeben. Wie groß muss die Masse des Eiswurfels ¨ mEis (gemessen in g) sein, damit nach dem vollständigen Schmelzen die Temperatur des Wassers gerade T1 = 5◦C beträgt? (Gib den berechneten Wert gerundet auf drei signifikante Stellen an.)

Hinweis: Spezifische Wärmekapazität von Eis: cEis = 2.0 Jg−1K−1 . Schmelzwärme: ∆QS = 333.5 Jg−1 . Schmelztemperatur: TS = 0◦C."

Jensek81'scher Ansatz:
a) 0, 5l = 500 cm³ = 0, 5 dm³ = 0,5 * 10^-3 m
m*p* V = 1,0 g /cm³ * 0,5 * 10^-3 m³ = 500 g

Temperaturveränderung ∆ T = T2 - T1 = 20 Grad -- 5 Grad = 15 Grad

∆Q = cw * mw * ∆T = 5,2 J / g C * 500 g * 15 C = 31500 J

b) Zunächst wird das EIs von -18 Grad au f0 Graad erwämt. Dazu wird Wärme Q1 benötigt.

Q1 = m * c * ∆T = 2,0 J/kgK * 18 Grad = 36 kJ/kg
Dann wird Eis geschmolzen. Dazu Wärme Q2

Q2 = m * q = m * 335, Jg^-1
Um das geschmolzene Wasser auf 5 Grad zu erwärmen ist Q3 erforderlich.

Q3 = m * c * ∆T = m * 4,2 Jg^-1/K^^1 * 5 K = m * 21 kJ/Kg

Q = Q1 + Q2 + Q3

m * 36 kJ/kg + m * 333,5 kJ/Kg + m * 21 kJ/kg = 31500 J
m (36 kJ/Kg + 333,35 kj/kg + 21kJ/Kg) = 31500 J
m + 390,5 kJ/kg = 31500 J

=> m = 31500 J/ 390,5 kJ/g = 80,66 g

Der Eiswrüfel hat 80,66 g

Kann das sein? oder ist das Kakolores?

Mit freundlichen Grüßen.
Ach, jetzt hätt ich schon fast ausversehen meinen Klarnamen geschrieben.
Seht ihr, soweit kommt's noch. Hahaha
Also, nochmal:

Mit freundlichen Grüßen,
Jensek81

Ask Me Anything: Blickwechsel

Du stellst die Fragen, ein außergewöhnlicher Nutzer antwortet! Begegne mit Deinen Fragen anderen Menschen hautnah und persönlich.

Ask Me Anything: Themenspecials

Im gutefrage Themenspecial beantworten Verbände, Organisationen und Personen des öffentlichen Lebens Deine Fragen zu aktuellen Themen.
Was denkt ihr von dieser Theory?

Hypothesis on the Multi-Sheet Structure of Spacetime and the Role of Dark Energy in Gravitational Dynamics

This hypothesis proposes a novel structure of spacetime, conceptualized as being comprised of multiple, distinct "sheets" that coexist and interact within a higher-dimensional continuum. Each sheet is characterized by its interaction with different classes of physical entities: one sheet interacts predominantly with classical macroscopic objects (e.g., planets, stars), while another is primarily influenced by quantum entities (e.g., photons), manifesting both particle and wave characteristics. This dual interaction model aims to bridge the gap between classical and quantum descriptions of gravitational phenomena.

Central to this hypothesis is the role of dark energy, postulated here as the fundamental constituent of these spacetime sheets. Unlike the conventional understanding of dark energy as a uniformly distributed force with negative pressure driving the accelerated expansion of the universe, this hypothesis reinterprets dark energy's negative pressure trait not as a literal repulsion but as an intrinsic tendency towards homogeneity and unity across spacetime. Dark energy, in this framework, seeks to minimize spatial curvature variations induced by mass-energy distributions, striving for a state of uniformity within each sheet and across the multi-sheet structure.

This intrinsic property of dark energy to "straighten" spacetime—an endeavor to achieve a uniform state—provides a novel mechanism for counteracting gravitational curvature. It suggests that the observed cosmological effects attributed to dark energy, such as the accelerated expansion of the universe, might be a macroscopic manifestation of its fundamental tendency towards homogenizing spacetime curvature.

Moreover, the hypothesis speculates on the nature of gravitational waves, suggesting that these phenomena could arise from interactions between different spacetime sheets, mediated by quantum and classical entities. Such interactions could lead to variations in gravitational constants or apparent deviations in physical constants, interpreted here not as measurement inaccuracies but as real effects stemming from the dynamic interplay of multi-sheet spacetime curvature and dark energy's unifying properties.

This multi-sheet spacetime model, underpinned by a reimagined role for dark energy, presents a framework for exploring the interface between general relativity and quantum mechanics. It offers a potential pathway for addressing unresolved questions in cosmology, such as the nature of dark energy, the mechanism of gravitational wave propagation, and the variability of fundamental constants. Critical to the advancement of this hypothesis will be the development of a rigorous mathematical formulation and the identification of testable predictions that can be empirically validated or falsified through observational and experimental evidence.