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I would like to add a microscopic perspective to this question that were mentioned in comments but which I think deserves more attention. A macroscopic body expands when heated because the average sep …

temperature, where the hotter body is the one which the heat flows from. … On the other hand, the efficiency of a reversible engine is $$\eta=1-\frac{T_H}{T_C},$$ where $T_H$ and $T_C$ are the absolute temperature of the hot and cold sources, respectively. …

In order to define a scale of temperature we need to follow three steps: To choose a thermometric property which changes with temperature; To define two reference points; To define an interpolation. … Hence if we plot temperature in Fahrenheit versus volume we obtain a straight line (dotted line), i.e., As we can see, the dotted line, which is a straight line also provides a function between the …

The kinetic theory also states that the collisions of the particles with walls are elastic, therefore there is no kinetic energy lost. Regarding the first law, it only says how energy can be exchanged …

In fact your perception of hotness is not due to temperature but rather due to heat transfer rate from the medium to your body's sensory receptors. … An objective definition of hotness would be given by the temperature of the body and since sand and water (in thermal equilibrium) are at the same temperature, we cannot say one is hotter than the other …

This means that given the same amount of heat, the temperature change is higher for fat than for water. You can see in this table as normally fatty food has greater specific heat. … Moreover, oils have higher boiling points so the cheese can reach a temperature above $100\ \mathrm{^\circ C}$. Edit Both vegetable and animal oils are made of nonpolar molecules. …

From a logical and thermodyamic point of view, the definition of temperature must be given by the Zeroth Law of Thermodynamics. Let us say we do not know what temperature is. … _1$ is determined by $$T_1=\frac{T_2}{1-\eta_R}.$$ Note that there is no longer arbitrariness about the concept of temperature, except for the choice the the temperature of the cold source. …

Now recall that temperature is actually a measure of molecular (or particle) agitation. Greater the temperature, grater the agitation. … The unit of entropy is unit of heat by unit of temperature. …

A heat flow through a finite difference of temperature is irreversible because it does not satisfy the definition of reversibility. … To illustrate, let us consider a system at temperature $T$ in thermal equilibrium - that is at the same temperature - with a thermal reservoir. …

The "standard value" in this case refers to the concept of empirical temperature. The link explains with more detail the difference between empirical and thermodynamic temperatures. … In order to define an empirical temperature you need: A substance with a thermometric property (such as mercury and its volume expansion). …

temperature $T_h$ is determined by $$T_1=\frac{T_2}{1-\eta_R}. … \tag{2}$$ This is an absolute temperature since it can be checked by any reversible engine with no ambiguities. Note that this not define temperature, since this is done only by the zeroth law. …

You are doing a common misconception of the second law. The Kelvin statement of the Second Law says it impossible to have a process whose only effect is convert heat into work. The term "only effect" …

The definition of an empirical temperature is basically what the Zeroth Law of Thermodynamics does. Let us suppose we do not have any prior knowledge about temperature. … Each class is labeled by a number $T>0$ which we shall call temperature. The Zeroth Law allows us establish thermal equilibrium just in terms of temperature. …

Note that this definition of heat does not require the definition of temperature (which is precisely given by the zeroth law) and in fact it can be used to define the calorimetric concept of temperature …

It is not true in general that liquids expand linearly with the temperature but it might be true for a particular liquid and a particular temperature scale. Let us say you have mercury. … If you choose a linear interpolation, then, by definition, the volume of Mercury will be a linear function of the temperature $\mathrm{X}$. …