Question

What happens to the energy in a closed system?

Answer 1

can exchange energy with its surroundings through heat and work transfer. In other words, work and heat are the forms that energy can be transferred across the system boundary.

Answer 2

The law of conservation of energy is an important law of physics. Basically, it says that while energy can turn from one kind into another, the total amount of energy doesn't change. This law applies only to closed systems, meaning systems that can't exchange energy with their environment