Which item has the most thermal energy?
A. 1 kg hot water just below the boiling point
B. 1 kg ice
C. 1 kg boiling water
D. 1 kg cold water
Answer (1)
The problem asks which of the four items has the most thermal energy. By considering the temperature and phase of each item, we determine that boiling water has the most thermal energy because it is at the highest temperature and in the liquid phase. Therefore, the answer is C.
Explanation
Understanding the Problem We are given four items and we need to determine which one has the most thermal energy. The items are:
A. 1 kg hot water just below the boiling point B. 1 kg ice C. 1 kg boiling water D. 1 kg cold water
To determine which item has the most thermal energy, we need to consider both the temperature and the phase of each item. Thermal energy is the total kinetic and potential energy of the molecules within a substance. Higher temperature generally means higher thermal energy, and phase changes also involve changes in thermal energy.
Analyzing Each Item Let's analyze each item:
A. 1 kg hot water just below the boiling point: This water is close to 100°C and is in the liquid phase.
B. 1 kg ice: This is water in the solid phase (ice). Its temperature is at or below 0°C.
C. 1 kg boiling water: This water is at 100°C and is in the liquid phase.
D. 1 kg cold water: This water is in the liquid phase, and its temperature is significantly below room temperature.
Eliminating Options Comparing the items, we can eliminate some options:
Cold water (D) will have less thermal energy than hot water (A) and boiling water (C) because its temperature is much lower.
Ice (B) will have less thermal energy than liquid water at the same temperature because energy is required to change from the solid phase (ice) to the liquid phase (water).
Comparing Hot and Boiling Water Now we need to compare hot water (A) and boiling water (C). Both are in the liquid phase, but boiling water is at 100°C, while hot water is just below the boiling point (slightly less than 100°C). Therefore, boiling water (C) has a slightly higher temperature, and thus more thermal energy, than hot water (A).
Conclusion Therefore, the item with the most thermal energy is 1 kg of boiling water (C).
Examples
Understanding thermal energy is crucial in many real-world applications. For instance, in cooking, knowing which item has more thermal energy helps determine how quickly food will cook. Similarly, in engineering, understanding thermal energy is essential for designing efficient heating and cooling systems. For example, a car radiator uses water to absorb thermal energy from the engine, preventing it from overheating. The principles of thermal energy are also fundamental in climate science, where understanding the distribution of thermal energy in the atmosphere and oceans is vital for predicting weather patterns and climate change.
