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This law was postulated in the 1930s, after the first and second laws of thermodynamics had been developed and named. It is called the zeroth law because it comes logically before the first and second laws (discussed in Thermodynamics ). An example of this law in action is seen in babies in incubators: babies in incubators normally have very few clothes on, so to an observer they look as if they may not be warm enough. However, the temperature of the air, the cot, and the baby is the same, because they are in thermal equilibrium, which is accomplished by maintaining air temperature to keep the baby comfortable.

Does the temperature of a body depend on its size?

No, the system can be divided into smaller parts each of which is at the same temperature. We say that the temperature is an intensive quantity. Intensive quantities are independent of size.

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Section summary

  • Temperature is the quantity measured by a thermometer.
  • Temperature is related to the average kinetic energy of atoms and molecules in a system.
  • Absolute zero is the temperature at which there is no molecular motion.
  • There are three main temperature scales: Celsius, Fahrenheit, and Kelvin.
  • Temperatures on one scale can be converted to temperatures on another scale using the following equations:
    T º F = 9 5 T º C + 32 size 12{T rSub { size 8{°F} } = { {9} over {5} } T rSub { size 8{°C} } +"32"} {}
    T º C = 5 9 T º F 32 size 12{T rSub { size 8{°C} } = { {5} over {9} } left (T rSub { size 8{°F} } - "32" right )} {}
    T K = T º C + 273 . 15 size 12{T rSub { size 8{K} } =T rSub { size 8{°C} } +"273" "." "15"} {}
    T º C = T K 273 . 15 size 12{T rSub { size 8{°C} } =T rSub { size 8{K} } - "273" "." "15"} {}
  • Systems are in thermal equilibrium when they have the same temperature.
  • Thermal equilibrium occurs when two bodies are in contact with each other and can freely exchange energy.
  • The zeroth law of thermodynamics states that when two systems, A and B, are in thermal equilibrium with each other, and B is in thermal equilibrium with a third system, C, then A is also in thermal equilibrium with C.

Conceptual questions

What does it mean to say that two systems are in thermal equilibrium?

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Give an example of a physical property that varies with temperature and describe how it is used to measure temperature.

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When a cold alcohol thermometer is placed in a hot liquid, the column of alcohol goes down slightly before going up. Explain why.

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If you add boiling water to a cup at room temperature, what would you expect the final equilibrium temperature of the unit to be? You will need to include the surroundings as part of the system. Consider the zeroth law of thermodynamics.

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Problems&Exercises

What is the Fahrenheit temperature of a person with a 39 . 0 º C size 12{"39" "." 0°C} {} fever?

102 º F size 12{"102"°F} {}

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Frost damage to most plants occurs at temperatures of 28 . 0 º F size 12{"28" "." 0°F} {} or lower. What is this temperature on the Kelvin scale?

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To conserve energy, room temperatures are kept at 68 . 0 º F size 12{"68" "." 0°F} {} in the winter and 78 . 0 º F size 12{"78" "." 0°F} {} in the summer. What are these temperatures on the Celsius scale?

20 . 0 º C size 12{"20" "." 0°C} {} and 25 . 6 º C size 12{"25" "." 6°C} {}

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A tungsten light bulb filament may operate at 2900 K. What is its Fahrenheit temperature? What is this on the Celsius scale?

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The surface temperature of the Sun is about 5750 K. What is this temperature on the Fahrenheit scale?

9890 º F size 12{"9890"°F} {}

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One of the hottest temperatures ever recorded on the surface of Earth was 134 º F size 12{"134"°F} {} in Death Valley, CA. What is this temperature in Celsius degrees? What is this temperature in Kelvin?

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(a) Suppose a cold front blows into your locale and drops the temperature by 40.0 Fahrenheit degrees. How many degrees Celsius does the temperature decrease when there is a 40 . 0 º F size 12{"40" "." 0°F} {} decrease in temperature? (b) Show that any change in temperature in Fahrenheit degrees is nine-fifths the change in Celsius degrees.

(a) 22 . 2 º C size 12{"22" "." 2°C} {}

(b) Δ T º F = T 2 º F T 1 º F = 9 5 T 2 º C + 32 . 0 º 9 5 T 1 º C + 32 . 0 º = 9 5 T 2 º C T 1 º C = 9 5 Δ T º C

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(a) At what temperature do the Fahrenheit and Celsius scales have the same numerical value? (b) At what temperature do the Fahrenheit and Kelvin scales have the same numerical value?

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Questions & Answers

Discuss the differences between taste and flavor, including how other sensory inputs contribute to our  perception of flavor.
John Reply
taste refers to your understanding of the flavor . while flavor one The other hand is refers to sort of just a blend things.
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While taste primarily relies on our taste buds, flavor involves a complex interplay between taste and aroma
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omeprazole
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Omeprazole Cimetidine / Tagament For the complicated once ulcer - kit
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Not really sure
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to drain extracellular fluid all over the body.
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The lymphatic system plays several crucial roles in the human body, functioning as a key component of the immune system and contributing to the maintenance of fluid balance. Its main functions include: 1. Immune Response: The lymphatic system produces and transports lymphocytes, which are a type of
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Anatomy is the identification and description of the structures of living things
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Anatomy is the study of the structure of the body, while physiology is the study of the function of the body. Anatomy looks at the body's organs and systems, while physiology looks at how those organs and systems work together to keep the body functioning.
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Enzymes are proteins that help speed up chemical reactions in our bodies. Enzymes are essential for digestion, liver function and much more. Too much or too little of a certain enzyme can cause health problems
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it is because of the enzyme that the stomach produce that help the stomach from the damaging effect of HCL
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37 degrees selcius
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36.5
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37°c
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the normal temperature is 37°c or 98.6 °Fahrenheit is important for maintaining the homeostasis in the body the body regular this temperature through the process called thermoregulation which involves brain skin muscle and other organ working together to maintain stable internal temperature
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anaemia is the decrease in RBC count hemoglobin count and PVC count
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Organ Systems Of The Human Body (Continued) Organ Systems Of The Human Body (Continued)
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Source:  OpenStax, College physics. OpenStax CNX. Jul 27, 2015 Download for free at http://legacy.cnx.org/content/col11406/1.9
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