Internal energy and its change

Equipment

• Virtual gas container with randomly moving particles
• Sliders “Nhiệt nhận Q” (heat in), “Công lên hệ W” (work on system), “Nhiệt độ ban đầu” (initial temperature)
• Energy-balance readout and particle-speed view

Procedure

1. Add heat only

   Set the work slider W to zero and raise the heat input Q. The particles speed up and the readout grows: with W=0, all of Q becomes internal energy, $\Delta U=Q$. Read $\Delta U$ and the implied temperature change.

2. Add work only

   Return Q to zero and raise the work slider — the model's piston does work on the gas. Check that the same energy increase results: $\Delta U=W_{\mathrm{on}}$. Compare the particle speeds with the pure-heating case at equal $\Delta U$.

3. Combine heat and work

   Set both Q and W to positive values, note their sum, and check $\Delta U=Q+W_{\mathrm{on}}$ on the readout. Then pick a target $\Delta U$ and find two different (Q, W) pairs that reach it — energy is a state function, indifferent to the path.

4. Vary the starting point

   Change the initial-temperature slider and repeat one transfer. The same Q or W produces the same $\Delta U$ regardless of the starting temperature — evidence that heat and work are modes of transfer, not properties of the gas.

Simulation

Experiment history

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