| Difficulty | Secondary School | High school/other |
| ★ | Basic | Easy |
| ★★ | Demanding | Basic |
| ★★★ | Demanding | |
| ★★★★ | Difficult | |
| ★★★★★ | Very difficult |
What is the average velocity on the outer surface in the circular orbit of the wheel? (average speed at the rim of the wheel?)
Answer: $1{,}2\ m/s$