Introduction To Physics

Introduction To Physics 

Temperatures

Temperatures 

Three Big Temperature Scales

Since we're going to be talking about heat, temperatures, and energy, we wanted to introduce you to how temperature is measured. The big three are Fahrenheit, Celsius and Kelvin. Even though scientists may use only a few scales to measure temperature, there are dozens of types of devices that measure temperatures. All of these devices are called thermometers because they measure temperature. There are thermometers to measure your body temperature, the temperature in your oven, and even the temperature of liquid oxygen. 

Fahrenheit is the Classic

Fahrenheit is the classic English system of measuring temperatures. Water freezes at 32 degrees Fahrenheit and boils at 212 degrees. The scale was created by Gabriel Daniel Fahrenheit in 1724 and divides the difference between the boiling point and freezing point of water into 180 equal degrees. You will probably be asked to convert temperatures back and forth from Fahrenheit to Celsius. Here's the formula: (Fahrenheit-32)*5/9=Celsius. 

Celsius Based on Water

Celsius is the modern system of measuring temperature. It fits in with much of the metric system and has nice round numbers. In Celsius, we call the freezing point of water 0 degrees Celsius, and the boiling point 100 degrees Celsius. Then the scale is divided into 100 equal degrees between those two points. The scale used to be known as centigrade but the name was changed several years ago. Both Celsius and Fahrenheit are used when discussing our day-to-day weather temperatures. Celsius degrees are larger than Fahrenheit degrees. 

Kelvin to Absolute Zero

Kelvin is an important scale used in most of science. The big difference is that it is based on a single point (absolute zero) which is given a value of 0 degrees. From there, the scale increases by degrees that are the same size as Celsius degrees. It is a scale that is based on energy content, rather than on arbitrary temperature values like the other two scale (based on water). Water freezes at the value 273.15 and boils at 373.15 Kelvin. The word "Kelvin" comes from Lord Kelvin, who did a lot of work with temperatures. 

Thermodynamics

Thermodynamics

Heat and Thermal Energy

When scientists originally studied thermodynamics, they were really studying heat and thermal energy. Heat can do anything: move from one area to another, get atoms excited, and even increase energy. Did we say energy? That's what heat is. When you increase the heat in a system, you are really increasing the amount of energy in the system. Now that you understand that fact, you can see that the study of thermodynamics is the study of the amount of energy moving in and out of systems. 

Heat of Atoms

Now all of this energy is moving around the world. You need to remember that it all happens on a really small scale. Energy that is transferred is at an atomic level. Atoms and molecules are transmitting these tiny amounts of energy. When heat moves from one area to another, it's because millions of atoms and molecules are working together. Those millions of pieces become the energy flow throughout the entire planet. 

Heat Movement

Heat moves from one system to another because of differences in the temperatures of the systems. If you have two identical systems with equal temperatures, there will be no flow of energy. When you have two systems with different temperatures, the energy will start to flow. Air mass of high pressure forces large numbers of molecules into areas of low pressure. Areas of high temperature give off energy to areas with lower temperature. There is a constant flow of energy throughout the universe. Heat is only one type of that energy.