Temperature

Find the complete information with images at:

http://www.physicsclassroom.com/Class/thermalP/

Lesson 01: Heat and Temperature. a, b & c.

Eureka! Video Thermal Expansion & Contraction http://youtu.be/I7w_Qv5_h4c
Using balloons to illustrate the process, Eureka! shows how, when matter gets hot, its molecules go faster and the solid, liquid, or gas expands. Conversely, when matter gets cold, its molecules go slower, and the solid, liquid, or gas contracts.

Eureka! Video Measuring Temperature http://youtu.be/YWJHNG5y5F0
Eureka! shows viewers how Swedish scientist Anders Celsius invented the Celsius thermometer, using the expansion of mercury as a measure of temperature

Temperature and Thermometers
We all have a feel for what temperature is. We even have a shared language that we use to qualitatively describe temperature. The water in the shower or bathtub feels hot or cold or warm. The weather outside is chilly or steamy. We certainly have a good feel for how one temperature is qualitatively different than another temperature. We may not always agree on whether the room temperature is too hot or too cold or just right. But we will likely all agree that we possess built-in thermometers for making qualitative judgments about relative temperatures.

What is Temperature?
Despite our built-in feel for temperature, it remains one of those concepts in science that is difficult to define. It seems that a tutorial page exploring the topic of temperature and thermometers should begin with a simple definition of temperature. But it is at this point that I'm stumped. So I turn to that familiar resource, Dictionary.com ... where I find definitions that vary from the simple-yet-not-too-enlightening to the too-complex-to-be-enlightening. At the risk of doing a belly flop in the pool of enlightenment, I will list some of those definitions here:

•The degree of hotness or coldness of a body or environment.
•A measure of the warmth or coldness of an object or substance with reference to some standard value.
•A measure of the average kinetic energy of the particles in a sample of matter, expressed in terms of units or degrees designated on a standard scale.
•A measure of the ability of a substance, or more generally of any physical system, to transfer heat energy to another physical system.
•Any of various standardized numerical measures of this ability, such as the Kelvin, Fahrenheit, and Celsius scale.


Celsius Temperature Scale

The thermometer calibration process described above results in what is known as a centigrade thermometer. A centigrade thermometer has 100 divisions or intervals between the normal freezing point and the normal boiling point of water. Today, the centigrade scale is known as the Celsius scale, named after the Swedish astronomer Anders Celsius who is credited with its development. The Celsius scale is the most widely accepted temperature scale used throughout the world. It is the standard unit of temperature measurement in nearly all countries, the most notable exception being the United States. Using this scale, a temperature of 28 degrees Celsius is abbreviated as 28°C.

Fahrenheit temperature scale

Traditionally slow to adopt the metric system and other accepted units of measurements, the United States more commonly uses the Fahrenheit temperature scale. A thermometer can be calibrated using the Fahrenheit scale in a similar manner as was described above. The difference is that the normal freezing point of water is designated as 32 degrees and the normal boiling point of water is designated as 212 degrees in the Fahrenheit scale. As such, there are 180 divisions or intervals between these two temperatures when using the Fahrenheit scale. The Fahrenheit scale is named in honor of German physicist Daniel Fahrenheit. A temperature of 76 degree Fahrenheit is abbreviated as 76°F. In most countries throughout the world, the Fahrenheit scale has been replaced by the use of the Celsius scale.

Temperatures expressed by the Fahrenheit scale can be converted to the Celsius scale equivalent using the equation below:

°C = (°F - 32°)/1.8

Similarly, temperatures expressed by the Celsius scale can be converted to the Fahrenheit scale equivalent using the equation below:

°F= 1.8•°C + 32°


The Kelvin Temperature Scale

While the Celsius and Fahrenheit scales are the most widely used temperature scales, there are several other scales that have been used throughout history. For example, there is the Rankine scale, the Newton scale and the Romer scale, all of which are rarely used. Finally, there is the Kelvin temperature scale, which is the standard metric system of temperature measurement and perhaps the most widely used temperature scale used among scientists. The Kelvin temperature scale is similar to the Celsius temperature scale in the sense that there are 100 equal degree increments between the normal freezing point and the normal boiling point of water. However, the zero-degree mark on the Kelvin temperature scale is 273.15 units cooler than it is on the Celsius scale. So a temperature of 0 Kelvin is equivalent to a temperature of -273.15 °C. Observe that the degree symbol is not used with this system. So a temperature of 300 units above 0 Kelvin is referred to as 300 Kelvin and not 300 degree Kelvin; such a temperature is abbreviated as 300 K. Conversions between Celsius temperatures and Kelvin temperatures (and vice versa) can be performed using one of the two equations below.

°C = K - 273.15°

K = °C + 273.15

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COLEGIO ANDES DE MAZATLÁN SECCIÓN SECUNDARIA
CIENCIAS 2 (FÍSICA) SEGUNDO GRADO

QUIZ 19. TEMPERATURA

Alumn@: ___________________________________________ Calif.: _____

I. Selecciona la respuesta correcta:

1. Cuando un objeto se calienta aumenta el movimiento de las partículas (átomos y moléculas) que lo conforman. Por lo tanto, la medida de la energía cinética promedio de las partículas corresponde a:
A) La temperatura B) La presión C) La dilatación D) El calor

2. Al calentar un cuerpo, aumenta la energía cinética de las moléculas, produciéndose choques más o menos violentos, según la cantidad de calor entregada. Al valor promedio de ese movimiento de partículas se le denomina:
A) Solubilidad B) Energía térmica
C) Temperatura D) Inercia

3. Observa la siguiente gráfica que describe el cambio de longitud de un tubo de hierro con la temperatura: ¿Cuál es la longitud aproximada del tubo a una temperatura de 80 °C?
A) 300.30 m B) 300.25 m
C) 300.23 m D) 300.20 m

4. ¿Por qué dos cuerpos de distinto material a la misma temperatura se llegan a sentir uno más caliente que otro?
A) Por la forma como se conduce el calor a través de ellos.
B) Por la forma como cada uno alcanza la temperatura del lugar.
C) Por la forma como se emite el calor en cada uno de los materiales.
D) Por la forma como la temperatura de uno modifica a la del otro.

5. ¿Por qué la Torre Eiffel de París, que está construida con piezas metálicas, tiene una altura mayor cuando la temperatura es muy alta en verano?
A) Porque debido a la alta absorción de calor por el metal, éste se dilata y aumenta de tamaño.
B) Porque debido a la alta emisión de calor por el metal, éste se dilata y aumenta de tamaño.
C) Porque debido a que la energía absorbida y emitida por el metal es igual, éste se dilata y aumenta de tamaño.
D) Porque debido a que la energía calorífica cedida es menor que la temperatura, el metal se dilata y aumenta de tamaño.

6. Líquido que se utiliza en la construcción de termómetros debido a su propiedad de expansión térmica uniforme.
A) Agua B) Cloro C) Bromo D) Mercurio

7. ¿Cómo miden los termómetros la temperatura?

8. Una persona enferma tiene fiebre de 40°C, ¿a qué temperatura corresponde el valor en grado Fahrenheit?
A) 104 °F B) 273 °F C) 32 °F D) -104 °F

9. El cero absoluto es una temperatura teórica donde no existe ningún movimiento en las partículas de la materia. ¿Cuánto vale el cero absoluto en grados centígrados?
A) -273 °C B) 0 °C C) 37 °C D) 100 °C

10. ¿A cuántos grados Fahrenheit equivale el que un día tenga una temperatura ambiente de 32 °C? Utiliza la fórmula °F = 1.8*(°C) + 32
A) 32°C B) 64°C C) 57.6 °C D) 89.6 °C