5.1 - Thermal Physics

Question 1

What is thermal equilibrium?

Answer 1

A state in which there is no flow of thermal energy between the objects involved. Objects in thermal equilibrium must be at the same temperature

Question 2

What is the absolute scale of temperature?

Answer 2

• aka thermodynamic scale of temperature
• a scale for measuring the temperature based on absolute zero and the triple point of pure water, with gradations equal to the size of the Celsius scale
• measured in Kelvin (K)

Question 3

What is absolute zero?

Answer 3

The lowest possible temperature, where substances have minimum internal energy

Question 4

What is a triple point?

Answer 4

For a given substance, the triple point is the specific temperature and pressure where all three phases of that substance can exist in thermodynamic equilibrium

Question 5

What happens if you place a hot object next to a cold one?

Answer 5

• there is a net flow of thermal energy from the hot object to the cold object
• the cold object gets warmer and the hot object gets cooler until they are in thermal equilibrium

Question 6

What is the zeroth law of thermodynamics?

Answer 6

If 2 objects are each in thermal equilibrium with a third, then all three must be in thermal equilibrium with each other

Question 7

What is the relationship between the Kelvin scale and the Celsius scale?

Answer 7

Temperature (kelvin) = temperature (celsius) + 273

Question 8

What is the kinetic model?

Answer 8

Describes how all substances are made up of atoms or molecules, which are arranged differently depending on the phase of the substance

Question 9

How are atoms arranged in a solid according to the kinetic model?

Answer 9

• atoms are regularly arranged
• they are packed closely together with strong electrostatic forces of attraction between molecules holding them in fixed positions
• they vibrate and so have kinetic energy

Question 10

How are atoms arranged in a solid according to the kinetic model?

Answer 10

• atoms are arranged irregularly
• they are packed closely together
• have more kinetic energy than solids, so can change position and flow past each other

Question 11

How are atoms arranged in a gas according to the kinetic model?

Answer 11

• atoms are irregularly arranged
• spaced far apart and take up the shape of the container, so take up a larger volume. Few intermolecular bonds between particles
• they move randomly with different speeds in different directions