1. Friction

2. Friction
All moving objects experience friction, a force that opposes the motion of moving objects as they move past one another

3. Without friction, every single surface would be more slippery than a sheet of ice Friction acts at the surface where two objects come in direct contact with one another

4. Sliding/Kinetic Friction
There are four main types of friction:
Static Friction
Sliding/Kinetic Friction
Rolling Friction
Fluid Friction

5. Static Friction
Static friction is the friction force that on objects that are not moving Static friction always acts in the direction opposite to that of the applied force

6. You experience static friction every time you take a step
You experience static friction every time you take a step. As you push off with every step, static friction between the ground and your shoe prevent your shoe from sliding

7. Sliding/Kinetic Friction
Sliding friction is a force that opposes the direction of motion of an object as it slides over a surface Because sliding friction is less than static friction, less force is needed to keep an object moving than to start moving it

9. Rolling Friction
Rolling Friction is the friction force that acts on rolling objects

10. Rolling friction is times less than static friction or sliding friction Because of this, it is easier to move a heavy object using a wheeled device

11. Fluid Friction
Friction also acts on objects moving through water or air (water vapor) Fluid friction opposes the motion of an object moving through a fluid

12. Fluid friction increases as the speed of the object increases Fluid friction acting on an object moving through the air is known as air resistance