Today's lesson is about friction. Friction is a force that resists the motion of two objects moving against each other. It is an important force in the world because it helps things move in certain ways, slows things down, and can even help objects stop after they are no longer in motion.
To better understand how friction works, let's use the example of a car driving on the road. The road is made up of two surfaces—the tire (rubbery material) and the asphalt (hard material). As the car moves forward, the tire rubs against the asphalt and friction is generated. The friction of the tire against the road is what provides the necessary traction for the car to move forward.
Friction is a result of the two surfaces interacting within what is called an elastic limit. That limit is the highest force a surface can generate without doing permanent damage to the surface material. Different surfaces have different elastic limits and therefore generate different amounts of friction.
In the case of a car driving on the road, the tire rubber is an elastic material that can generate enough friction for the car to move forward. However, if the tires were made of a different material, like metal, then the friction generated would be so great that the car wouldn’t be able to move.
Knowing how to manage and calculate friction can be useful for solving problems with movement, especially when it comes to physics. Furthermore, understanding friction is important when designing machines or products that need to move.
Now it's time to discuss what type of friction we need to consider in this lesson. We are going to focus on kinetic friction or sliding friction. It is the force that resists the motion of two surfaces moving against each other, like the tire and the asphalt.
To calculate the force of friction, we need to use the formula:
Friction force (in newtons) = coefficient of friction x normal force (in newtons)
The coefficient of friction is a number based on the two surfaces that interact. The normal force is the perpendicular force that acts on the two surfaces (i.e. the weight of the car).
We hope that this introduction to friction gives you a better idea of how it works and how to calculate the force of friction.
Thank you for your attention!