Practise treating monatomic ideal-gas internal energy as total random translational kinetic energy and calculating it from particle number, moles or temperature change.
This question is in two parts. Part 1 is about ideal gases and specific heat capacity. Part 2 is about simple harmonic motion and waves.
Part 1 Ideal gases and specific heat capacity
At the temperature of 350 K , the piston in (b) is now freed and the argon expands until its temperature reaches 300 K .
Explain, in terms of the molecular model of an ideal gas, why the temperature of argon decreases on expansion.
temperature is a measure of the average kinetic energy of the (must see "average molecules; kinetic" for the mark)
energy/momentum to move piston is provided by energy/momentum of molecules that collide with it;
the (average) kinetic energy of the gas therefore decreases;
Marking guidance:
Do not allow arguments in terms of loss of speed as a result of collision with a moving piston.
Part 2 Simple harmonic motion and waves