Types of Friction

1. Static Friction

1. • The frictional force that keeps an object at rest.
     
     

   • It must be overcome for the object to start moving.
     
     

   • Example: Pushing a heavy sofa — it doesn’t move at first because static friction is holding it.
     
     

2. Sliding (Kinetic) Friction

2. • The friction acting on objects that are already moving across a surface.
     
     

   • Usually less than static friction.
     
     

   • Example: A book sliding across a table.
     
     

3. Rolling Friction

3. • The friction that resists the motion of a rolling object.
     
     

   • Much smaller than sliding friction.
     
     

   • Example: Wheels of a car, a ball rolling on the ground.
     
     

4. Fluid Friction (Drag/Air Resistance)

4. • The friction that occurs when an object moves through a fluid (liquid or gas).
     
     

   • Example: Air resistance on a moving car, water resistance on a swimmer.

Examples of Friction Increased on Purpose (at home)

1. Shoe soles with grip – to prevent slipping while walking.
   
   

2. Doormats with rough surfaces – to clean dirt off shoes.
   
   

3. Rough broom bristles – to sweep floors effectively.
   
   

4. Non-slip mats in bathrooms – to prevent accidents.
   
   

5. Rug under furniture – to stop it from sliding.
   
   

Examples of Friction Reduced on Purpose (at home)

1. Sliding glass doors with rollers – to open and close easily.
   
   

2. Oil applied to squeaky door hinges – to make movement smooth.
   
   

3. Polished wooden floors – for easy movement of furniture.
   
   

4. Teflon-coated frying pans – so food doesn’t stick.
   
   

5. Drawer runners with ball bearings – to make drawers slide smoothly.

CIRCUIT SYMBOLS