Friction

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

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

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

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

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

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

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

Rolling friction is 100-1000 times less than static friction or sliding friction Because of this, it is easier to move a heavy object using a wheeled device

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

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