Answer
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Work Step by Step
The author told us to explain the concept of an isolated system to someone who never heard of it.
To simplify it, we say that the prison is an isolated system. It has its own rules and had nothing to do with changes happening outside its wall.
The people inside the walls of the prison interact with each other but there is no one from outside affecting them.
If someone was in prison and there is a military coup happened outside the walls of the prison, the rules of the country changed but the rules in this system, the prison, remain as usual since it has no relation to what is happening outside.
We have the same concept in physics. An isolated system consists of a group of interacting objects that the net external force exerted on it is zero. As an example, a gas in an isolated jar is an isolated system since the particles of the gas inside the jar are colliding with each other and with the walls of the jar, but it has no external force exerted on it.
