Thermodynamics: common misconceptions

If your child says… “No heat passes, so the temperatures must match.”

Ask together

Could insulation keep two bodies at different temperatures?

What’s true

Insulation can limit heat transfer even when temperatures differ.

If your child says… “The gas stores the heat it receives.”

Ask together

If work also increases internal energy, why call all that energy stored heat?

What’s true

Heat transfers energy across the boundary; internal energy belongs to the gas.

If your child says… “Both heat capacities must match.”

Ask together

What supplies the energy lifting the loaded piston?

What’s true

Fixed-volume heating increases internal energy without expansion work.

If your child says… “The temperature stays fixed, so no heat moves.”

Ask together

Where can compression energy go if the gas's internal energy stays unchanged?

What’s true

An ideal gas compressed at constant temperature releases heat equal to the work supplied.

If your child says… “Insulation keeps the temperature fixed.”

Ask together

If heat cannot enter, where does the energy for expansion work come from?

What’s true

Insulated ideal gas cools while doing work, but keeps its temperature during expansion into vacuum.

If your child says… “A cycle means zero heat and zero work.”

Ask together

Could equal incoming heat and outgoing work leave internal energy unchanged?

What’s true

Internal energy returns to its starting value, while net heat and work can remain nonzero.

If your child says… “The fridge only releases the heat it removes.”

Ask together

Where does the supplied work's energy go?

What’s true

The refrigerator also releases the energy supplied through work.

If your child says… “Anything done slowly is reversible.”

Ask together

Would friction's warming disappear simply because the gas returns to its starting state?

What’s true

Reversal must restore both the gas and its surroundings, leaving no change.