Assessment And Qualifications Alliance (AQA) GCSE Physics Practice Exam

A closed system is defined as one that allows energy to be exchanged with its surroundings while preventing the exchange of matter. This means that any energy transfers, such as heat or work, can occur, but no substances can enter or exit the system. For example, consider a sealed container of gas. The gas can expand or contract, and heat can be added or removed from the container, allowing energy transfer. However, the gas itself cannot escape the container, thus illustrating the characteristics of a closed system. In contrast, an open system allows both energy and matter to be exchanged, while an isolated system does not allow either energy or matter exchange, and a uniform system is not a standard term commonly used in thermodynamics. This distinction makes the closed system the correct answer because it accurately depicts the conditions described in the question.