Static Friction
Sample Solution
Real-world example of a system where static friction forces are required:
Walking
How static friction is used in walking:
When we walk, our feet push back against the ground to propel us forward. The static friction between our feet and the ground prevents us from slipping.
Full Answer Section
Normal force and how it relates to static friction:
The normal force is the force that is exerted perpendicular to the surface of contact between two objects. In the case of walking, the normal force is the force of our feet pressing down on the ground.
The static friction force is proportional to the normal force. This means that the more force we exert downward on the ground, the more static friction there will be. This is why it is easier to walk on a rough surface than on a smooth surface.
Static friction force:
The static friction force is the force that resists the motion of two objects that are in contact with each other. In the case of walking, the static friction force is the force that prevents our feet from slipping on the ground.
The static friction force is calculated as follows:
Static friction force = Coefficient of static friction * Normal force
Coefficient of static friction:
The coefficient of static friction is a measure of how much friction there is between two surfaces. It is a dimensionless number that ranges from 0 to 1. The higher the coefficient of static friction, the more friction there is between the two surfaces.
The coefficient of static friction for different materials is given in the following table:
| Material 1 | Material 2 | Coefficient of static friction |
|---|---|---|
| Rubber | Concrete | 0.8 |
| Wood | Concrete | 0.6 |
| Ice | Concrete | 0.1 |
Conclusion:
Static friction is an important force that allows us to walk. It is also an important force to consider in mechanical design. By understanding static friction, we can design systems that are safe and reliable.