| Difficulty | Secondary School | High school/other |
| ★ | Basic | Easy |
| ★★ | Demanding | Basic |
| ★★★ | Demanding | |
| ★★★★ | Difficult | |
| ★★★★★ | Very difficult |
What is the average force exerted to the tennis ball by the racket?
Tip: The impulse caused by force is equal to the change in impulse-momentum.
Answer: 440 N