Thermal Physics Q&A: Get Expert Help and Learn from Real-World Examples

What is the First Law of Thermodynamics? Give 1 situation wherein the first law can be applied and explain how it is applied.

The first law of thermodynamics
$\text{d}Q=\text{d}U+p\text{d}V-<!--\; -\; -->\mathrm{\mu <!--\; \mu \; -->}\text{d}N$
is equivalent to saying: Q is a differentiable real valued function of U,V and N, so that we can write $\text{d}Q=\frac{\mathrm{\partial <!--\; \partial \; -->}Q}{\mathrm{\partial <!--\; \partial \; -->}U}\text{d}U+\frac{\mathrm{\partial <!--\; \partial \; -->}Q}{\mathrm{\partial <!--\; \partial \; -->}V}\text{d}V+\frac{\mathrm{\partial <!--\; \partial \; -->}Q}{\mathrm{\partial <!--\; \partial \; -->}N}\text{d}N$, and $\frac{\mathrm{\partial <!--\; \partial \; -->}Q}{\mathrm{\partial <!--\; \partial \; -->}U}=1$. Also, we define $p=\frac{\mathrm{\partial <!--\; \partial \; -->}Q}{\mathrm{\partial <!--\; \partial \; -->}V}$ and $-<!--\; -\; -->\mathrm{\mu <!--\; \mu \; -->}=\frac{\mathrm{\partial <!--\; \partial \; -->}Q}{\mathrm{\partial <!--\; \partial \; -->}N}$
Is that it?

Bernoulli's principle is an example of which law of thermodynamics. Explain why?

Suppose you mix two identical blocks of metal, one having a temperature of ${10}^{\circ <!--\; \circ \; -->}$ and the other ${20}^{\circ <!--\; \circ \; -->}$. Is it possible for the cold block to cool to $5^{\circ <!--\; \circ \; -->}C$ and the warm block to warm to ${25}^{\circ <!--\; \circ \; -->}C$?

A. Yes, because it adheres to the second law of thermodynamics.
B. No, because it will violate the zeroth law of thermodynamics.
C. Yes, because it adheres to the zeroth law of thermodynamics.
D. No, because it will violate the first law of thermodynamics.

An imaginary machine takes 9,000J of heat from a hot reservoir and 3,000 J of heat from a cold reservoir and produces 12,000 J of work. What can be said about this machine? O It violates both the first and second laws of thermodynamics. It violates the second law of thermodynamics but not the first law. It violates the first law of thermodynamics but not the second law. O It does not violate either the first or the second law of thermodynamics.

What are the state functions telling me or how are they related to total energy?

Why can a system extract heat from an environment at constant temperature for free?

A superconducting ring can carry a current for an indefi nite length of time. Isn’t this a perpetual motion machine, which violates the fi rst or second law of thermodynamics? Explain.

Is n=1 (degrees of freedom) for monatomic?

Which material is a heat source for the other three materials?
Presented is a closed energy system containing equal masses of iron (55 degrees C), basalt (45 degrees C), and water (20 degrees C); air is 30 degrees C.
Which material is a heat source for the other three materials? 1) iron 2) basalt 3) air 4) water - Is the answer iron because it has the most heat?
During the first hour, the total energy in the system will 1) decrease, only 2) increase, only 3) decrease, then increase 4) remain the same - (Shouldn't it remain the same because of the conservation of energy?)
Also during the first hour, the temperature of the water will 1) decrease 2) increase 3) remain the same - (I think it will increase because it acts as a heat sink? Or maybe it will remain the same because water has the highest specific heat?)
Helping me understand one or all of these would be a great help!

Why does temperature remain constant when water is boiling?

A rigid tank initially contains saturated vapor at 0,35 MPa. Then heat transferred to water until its temperature is ${400}^{\circ <!--\; \circ \; -->}C$. Determine the heat transfer during this process, in kJ/kg.

Can we show that the helmholtz free energy at equilibrium is minimized from its second derivative?

Using the free energy of a monatomic ideal gas, derive the ideal gas law

Calculate how much energy (kJ) is required to heat a liter of water from ${30}^{\circ <!--\; \circ \; -->}C$ to saturated liquid at normal boiling point

What would be the temperature of the resultant mixture?
The question in my textbook reads
100 g of water is supercooled to -${10}^{\circ <!--\; \circ \; -->}$C. At this point, due to some disturbance mechanised or otherwise some of it suddenly freezes to ice. What will be the temperature of the resultant mixture and how much mass would freeze?
I am well aware of the concepts and principle of Calorimetry but I can't seem to get a clear picture of the question.
My doubts include -
1.Why doesn't the whole water in the beaker freeze?
2.Why does some part of the water in the beaker act as a source of heat to raise the temperature of the remaining water?
3.Why is the equilibrium attained at $0^{\circ <!--\; \circ \; -->}$C?

Is the loudness of a ball that you drop a measure of the amount of energy you put in to lift it?
When you lift a heavy object off the floor and raise it then you've exerted an amount of work/energy on that body. When you release the heavy object gravity exerts the same work/energy. But when you lift the ball nothing dramatic happens. You lift it and that's it. When you drop the ball there is a loud bang when the ball hits the floor. What accounts for this difference? It seems that it must be that there is an equivalent amount of energy in your body as in the sound (assuming that the floor doesn't change so that most of the energy goes into sound). Is this accurate reasoning? Can you do sound calorimetry?

Identify all the molecular modes of motion for water and without doing any calculation, write the expression for the related molecular partition function.

The first excited energy level of a hydrogen atom has an energy of 10.2 eV, if we take the ground-state energy to be zero. However, the first excited level is really four independent states, all with the same energy. We can therefore assign it an entropy of 8 = kIn 4, since for this given value of the energy, the multiplicity is 4. Question: For what temperatures is the Helmholtz free energy of a hydrogen atom in the first excited level positive, and for what temperatures is it negative?