Give examples of the beneficial and harmful effects of friction forces of all kinds.

Static friction force:
Useful action: people walk, objects stand on the floor:
Harmful effect: difficult to move objects.

Sliding friction force:
Useful action: you can control the speed of movement of bodies:
Harmful effect: the friction surface heats up, energy is lost, materials wear.

Rolling friction force:
Benefit: use in bearings to reduce sliding friction:
Harmful effect: the friction surface heats up, energy is lost, materials wear.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.