9.1 - Heat And Temperature Flashcards
Heating an object causes…
It’s temperature to rise.
What determines the temperature of objects/ tell me about kinetic theory.
To understand the concept of temperature, we need to think about materials in terms of the molecules from which they are made. According to the kinetic theory, when energy is supplied to an object the molecules in that object take up the energy as kinetic energy, and move faster. In solids, this is usually in the form of vibrations, whereas if we are considering a gas, we imagine the molecules whizzing around their container at a greater speed. It is this kinetic energy that determines the temperature. If the average kinetic energy of the molecules of a substance is greater, then it is at a higher temperature.
What’s it important to remember about kinetic energy
It’s important to remember that the internal kinetic energy on the atomic scale is separate from the idea of overall movement of the object. For example, as a cricket ball flies through the air, it has kinetic energy due to its overall movement. In addition to this, it’s molecules will be vibrating within it, and it is this internal aspect of the energy that determines the temperature.
A stationary piece of metal has no kinetic energy. Yet all its atoms are vibrating all the time. Although overall these tiny velocities must sum to zero (or else it would be moving), their kinetic energies give the object its temperature.
What is absolute temperature
Taking energy away from the molecules of a substance causes its temperature to become lower. If you imagine a situation in which energy is continuously being taken away from a collection of molecules, then there will come a moment when all the kinetic energy has been removed from the substance. The molecules will no longer be moving at all. At this point, the temperature is said to be absolute zero.
What’s absolute zero
When molecules are no longer moving at all within a substance
Different scales of temperature have historically placed zero…
In arbitrary places compared with the average internal kinetic energy of the molecules.
Tell me about the positions of zero temperatures on different scales
Anders celsius chose the freezing point of pure water as the zero on his temperature scale.
Daniel Gabriel Fahrenheit placed zero at 32 degrees the freezing point of water (in the exception that there would never be a temperature colder than 0 degrees F to measure!).
On the Celsius scale, what is absolute zero
-273.15 degrees C
On the Fahrenheit scale, what is absolute zero
-459.67 degrees F
What was Lord Kelvins temperature scale like
In 1848, Lord Kelvin define an absolute temperature scale which started with zero at absolute zero. For convenience, he made the gaps in his scale identical to those on the Celsius scale. This is known as the Kelvin scale of temperature, or sometimes as absolute temperature.
The Kelvin scale of temperature is also known as
Absolute temperature
