5.1 Thermal Physics

Question 1

Define internal energy

Answer 1

The sum of the random distribution of kinetic and potential energies of particles within their associated substance.

Question 2

What happens to particles at absolute 0? (In terms of energy)

Answer 2

There is minimum internal energy and there is no kinetic energy.

Question 3

Define Boyle’s Law

Answer 3

For a fixed mass, Pressure is inversely proportional to volume

Question 4

Define Charles Law

Answer 4

Pressure is proportional to temperature

Question 5

For a closed system, what is the change of internal energy

Answer 5

change in internal energy= heat added to system - work done by system

Question 6

For an open system, if pressure and volume is constant, why is internal energy constant at all temperatures?

Answer 6

E=3/2 pV
so internal energy is independent of temperature.
As temperature increases, particles have greater KE and according to Newton’s 2nd Law, change in momentum is 2mv.
-because temperature is constant, the moles of particles must leave container.