Which statement about friction in a system is true?

Question

1. Friction decreases the total energy of a system.
2. Friction converts some energy on the molecular scale to energy on the macroscopic scale.
3. Friction converts some energy on the macroscopic scale to energy on the molecular scale.
4. Friction increases the total energy of a system.

Answer 1

2. Friction converts some energy on the molecular scale to energy on the macroscopic scale.