⦁ A closed system never has external forces acting on it. Does this ever happen on Earth? What external forces to objects feel while on Earth?
A closed system refers to a system that does not exchange matter or energy with its surroundings. However, it is almost impossible to have a truly closed system on Earth, as external forces constantly act on objects due to the presence of various factors. Some of the external forces that objects experience on Earth include:
1. Gravitational force: All objects on Earth experience Earth's gravitational pull, which attracts them toward the center of the planet.
2. Frictional force: When objects come into contact with other surfaces, there is a force of friction acting against their motion. This force depends on the surfaces' roughness and the normal force between them.
3. Air resistance or drag force: When objects move through the Earth's atmosphere, air resistance opposes their motion. The magnitude of this force depends on the object's speed, size, shape, and the density of the air.
4. Magnetic force: Objects made of magnetic materials can experience magnetic forces when interacting with magnetic fields.
5. Electrostatic force: Charged objects can exert electrostatic forces on each other, either attracting or repelling one another, depending on their charges.
These are just a few examples of external forces that objects experience on Earth. In reality, there are numerous other forces at play, making it challenging to find a completely closed system without any external influences.