| Difficulty | Secondary School | High school/other |
| ★ | Basic | Easy |
| ★★ | Demanding | Basic |
| ★★★ | Demanding | |
| ★★★★ | Difficult | |
| ★★★★★ | Very difficult |
Specify the coefficient of kinetic friction between the body and the surface.
Answer: 0,11
Exercise 3.9 B
| Difficulty | Secondary School | High school/other |
| ★ | Basic | Easy |
| ★★ | Demanding | Basic |
| ★★★ | Demanding | |
| ★★★★ | Difficult | |
| ★★★★★ | Very difficult |
Determine the coefficient of static friction between the body and the substrate.
Answer: 0,77
Exercise 3.9 C
| Difficulty | Secondary School | High school/other |
| ★ | Basic | Easy |
| ★★ | Demanding | Basic |
| ★★★ | Demanding | |
| ★★★★ | Difficult | |
| ★★★★★ | Very difficult |
Determine the coefficient of kinetic friction between the body and the substrate.
Answer: 0,59
Exercise 3.9 D
| Difficulty | Secondary School | High school/other |
| ★ | Basic | Easy |
| ★★ | Demanding | Basic |
| ★★★ | Demanding | |
| ★★★★ | Difficult | |
| ★★★★★ | Very difficult |
Specify the coefficient of static friction.
Answer: 0,25
Exercise 3.9 E
| Difficulty | Secondary School | High school/other |
| ★ | Basic | Easy |
| ★★ | Demanding | Basic |
| ★★★ | Demanding | |
| ★★★★ | Difficult | |
| ★★★★★ | Very difficult |
a) How many percents of the bodys potential energy transforms to heat energy during the sliding? b) Specify the coefficient of the sliding friction.
Tip 1: Measure time and velocity at specific distance.
Tip 2: The principle of energy $E_{beginning}=E_{end}$ or the model of steady accelerating movement.
Tip 2: The principle of energy $E_{beginning}=E_{end}$ or the model of steady accelerating movement.
Answer: a) 95 % - 96 %; b) 0,22 – 0,24
Exercise 3.9 F
| Difficulty | Secondary School | High school/other |
| ★ | Basic | Easy |
| ★★ | Demanding | Basic |
| ★★★ | Demanding | |
| ★★★★ | Difficult | |
| ★★★★★ | Very difficult |
Determine the coefficient of sliding friction between the surface and the body.
Answer: $0{,}14$