Question

A bathtub is half full of warm water. How could the thermal energy of the water be increased? Check all that apply.

Add hot water to the tub.

Heat the water in the tub without adding more water.

Add more water at the same temperature to the tub.

Transfer the water to a smaller container.

Answer 1

Correct answers:

- Add hot water to the tub. — Yes. You add higher-temperature water (and mass), so total thermal energy increases.
- Heat the water in the tub without adding more water. — Yes. Raising the water's temperature increases its thermal energy.
- Add more water at the same temperature to the tub. — Yes. Thermal energy is proportional to mass as well as temperature, so more water at the same temperature increases total thermal energy.
- Transfer the water to a smaller container. — No. Moving the water alone does not change its mass or temperature, so its thermal energy stays the same (unless heat is added/lost during the transfer).