Which of the following would be an example of a closed system?

Question

A person pushing a refrigerator box across a rough floor

A water bucket being pulled up by rope from a well

A rolling oil drum across a smooth, frictionless marble floor

A large moving rock slowing down while ploughing through loose sand

Answer 1

A closed system is one that does not exchange matter with its surroundings, although it may exchange energy. Out of the options provided, the example that best represents a closed system is:

A rolling oil drum across a smooth, frictionless marble floor.

In this scenario, while the oil drum may exchange energy with the floor (e.g., through kinetic energy as it rolls), it does not lose or gain matter from its surroundings, making it the best fit for a closed system among the options.

The other options involve interactions with the environment that impact the movement of the objects (friction, pulling, and resistance from the sand), which means they are not closed systems.