| Difficulty | Secondary School | High school/other |
| ★ | Basic | Easy |
| ★★ | Demanding | Basic |
| ★★★ | Demanding | |
| ★★★★ | Difficult | |
| ★★★★★ | Very difficult |
There is a wire wrapped around a metal bar in the video. Determine the coefficient of static friction between the wire and the metal bar.
Tip: Google "capstan equation"
Answer: 0,11