Thermal Phyiscs Flashcards
How are particles in solids arranged
Particles vibrate about fixed positions in a regular lattice. They’re held in position by strong forces of attraction.
Remember to talk about amplitude and lattice
How are particles is liquids arranged
Particles are constantly moving around and are free to move past one another, but are attracted to each other.
How are particles in gases arranged
Particles are free to move around with constant random motion and no fixed shape.
There are no forces of attraction between particles in an ideal gas.
What is the kinetic model of matter
The idea that solids, liquids and gases are made up of tiny moving or vibrating particles is called the kinetic model of matter.
What did Robert Brown notice about particle of pollen in water. What is Brownian
Robert Brown noticed that tiny particles of pollen suspended in water moved with a random motion.
This type of movement (random) of any particle suspended in a fluid is known as Brownian motion.
How can Brownian motion be observed in the lab
You can observe Brownian motion in the lab:
• Put some smoke in a brightly illuminated glass jar and observe the particles using a microscope.
• The smoke particles appear as bright specks moving haphazardly from side to side, and up and down.
What did the Brownian motion of particles provide evidenced for?
This provided evidence for the existence of atoms or molecules in the air (that have energy) - (the kinetic model of matter).
Why does Brownian motion occur
The randomly moving water particles were hitting the pollen particles unevenly, causing this motion. He explained that these collisions were elastic and resulted in a transfer of momentum from the water molecules to the pollen grains.
What is internal energy
Internal energy is the sum of the kinetic and potential energy of the particles within a system.
Why does kenetic energy depend on
The kinetic energy of a particle depends on its mass and speed. Through kinetic theory, the average kinetic energy is proportional to temperature — the hotter the temperature, the higher the average kinetic energy.
What does potential energy depend
Potential energy is caused by interactions between particles and is based on their positions relative to each other.
Do all particles have the same energy
energies are randomly distributed amongst the particles.
When you heat a substance how does its energy change
When you heat a substance, you increase its temperature - thereby increasing the kinetic energy of the particles within it and its internal energy.
When a substance changes phase, describe how it’s energy and temperature change
When a substance changes phase, its internal energy changes, but its kinetic energy (and temperature) doesn’t. This is because the change of phase is altering the bonds and therefore potential energy of the particles.
How do you convert from degrees to kelvin
+273
What happens at 0K
At 0 K all particles have the minimum possible internal energy - everything theoretically stops
How is the absolute Scale different to the Celsius scale
The Celsius scale uses the freezing and boiling points of water (0 °C and 100 °C) to make a temperature scale
While the absolute scale does not depend on the properties of any particular substance,
What is absolute zero
0k
What is another name for the absolute scale
The thermodynamic scale
What can you say if body A and body B are both in equilibrium with body C
If body A and body B are both in thermal equilibrium with body C, then body A and body B must be in thermal equilibrium with each other.
What is the rule about thermal energy
Thermal energy is always transferred from regions of higher temperature to regions of lower temperature.
A, B and C are three identical metal blocks. A has been in a warm oven, B has come from a refrigerator and C is at room temperature, what happens when you put the blocks together
Suppose A, B and C are three identical metal blocks. A has been in a warm oven, B has come from a refrigerator and C is at room temperature.
Thermal energy flows from A to C and C to B until they all reach thermal equilibrium and the net flow of energy stops. This happens when the three blocks are at the same temperature.