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Challenge: Problem 4

Here is a more abstract problem to test your ability to manipulate the concepts we have been discussing. Consider the two items:
which say that we have the internal energy of a system changing while its temperature remains constant. There are a number of situations in which such conditions are possible: For example, in the isothermal compression of non-ideal gas, for which we would write down these items:
Think about this example and then find others of which there are at least five. All the examples have something in common with each other. As you work out your solutions and go through the discussion comments, try to decide what this common feature is.

1
U = 0		 2
conversion of work into internal energy by compression		 3
transition of energy from potential state to thermal state		 4
conversion of internal energy into work by expansion		 5
Q = 0
6
transfer of energy through adiabatic enclosure		 7
specific heat		 8
heat transfer		 9
W = 0		 10
enclosure permitting transfer of energy by heat and by work
11
change of phase of the kind: liquid vapour		 12
chemical energy		 13
U 0		 14
T 0		 15
H 0
16
thermal equilibrium		 17
uncertainty of change in U		 18
V = 0		 19
P = 0 		20
T = 0