When an ice cube melts on a table, it is gaining thermal energy. This is because the ice cube absorbs heat from its surroundings, causing it to change from a solid state to a liquid state.
To determine whether the ice cube is losing or gaining thermal energy, you can observe the temperature of the ice cube and its surroundings. If the ice cube is melting, it means that the temperature of the surroundings is higher than the freezing point of water (0°C or 32°F). The heat from the surroundings is transferred to the ice cube, causing it to gain thermal energy and melt.
Energy cannot be created or destroyed, according to the law of conservation of energy. The thermal energy that the ice cube gains comes from the surrounding environment, such as the air or the table it is placed on. As the ice cube absorbs this thermal energy, the surroundings may cool down slightly, but the total amount of energy in the system remains constant.
In summary, the ice cube gains thermal energy from its surroundings, causing it to melt. The thermal energy is transferred from the environment to the ice cube, and the total energy in the system remains unchanged.