Thermal physics

Internal energy definition

The sum of an objects random distribution of the kinetic and potential energies of its molecules

How can energy be transferred between 2 objects (2 ways)

Temperature difference between 2 objects

One object exerts a force on the other (work done)

What is thermal equilibrium

When there is no overall energy transfer by heating (both objects are same temperature)

The change of the internal energy of the object = (first law of thermodynamics)

The total energy transfer done by heating and work done

When a material changes state, what is changing in terms of molecules

Potential energy, not KE

When a material is getting hotter, what is changing in terms of molecules

The KE is increasing

What are the 3 relationships between p, V, T

Pressure proportional to Temperature (Pressure law)

Pressure is inversely proportional to Volume (Boyles’ law)

Volume is proportional to Temperature (Charles’ law)

Absolute zero definition

Where particles have 0 kinetic energy where no heat remains (0K)

Brownian motion definition

The random motion of particles

Work done equation for gases

W = pΔV (derived from p = F/A and W=Fd)

8 Assumptions for the kinetic theory equation

Molecules are in random motion

Molecules move in straight lines

Molecules obey newtons laws

Collision time is negligible compared to time between collisions

All collisions are elastic

Molecules do not exert forces on each other

V of molecules are negligible compared to V of gas#

We only consider translation KE

When a molecule collides with the wall of a container, what is the change in momentum

2mu

What is the average translation KE in a system

½ m (c_rms)²

Mean square speed meaning

The sum of the speeds of each particle squared divided by the number of particles