Friction can be classified into two types, static friction and kinetic friction. Kinetic friction can further be classified into sliding friction and rolling friction.
Friction can be classified as:
Static friction: The friction experienced between static bodies or bodies at rest. A box of heavy load is very difficult to lift or move, which is due to static friction.
Kinetic friction: Friction between two or more moving bodies. It can be classified as sliding friction and rolling friction.
Sliding friction: If a body slides over the surface of another body, the friction acting between surfaces in contact can be termed as sliding friction.
Rolling friction: If a body rolls over the surface of another body, the friction between the surfaces is called rolling friction.
Rolling friction is lesser than sliding friction. Hence, we have tyres in vehicles,trolleys so that friction can be lesser and motion of the body can be more.
Factors affecting friction:
There are three factors which can directly affect friction between two bodies or surfaces.
- Nature of area
- Weight of the bodies
- Area of contact.
Nature of the area:
Riding your bicycle on road is much easier than riding over the beach sand or over snow, it is due to the nature of area, that is road is a smooth surface whereas sand will have small stones and pebbles making the friction between tyre and sand higher, hence cycle cannot move smoothly. This is how nature of area influence the frictional force.
Weight of the bodies:
It is easy to ride your bicycle without any load, but when you take your friend for a ride (or) when you ride your bicycle with a load, it becomes difficult for you to pedal. This is because as weight increases the friction also increases.Since friction is a force that opposes the motion of the body, it becomes difficult for you to pedal.
Area of contact:
Take a birthday cone you can observe two ends, small circle and a big circle.
If you try to keep the cone in a table with bigger base it will be stable, but when you try to place the same with smaller end it will be difficult. If the area of contact is bigger, the friction will be more and hence the cone will not move. Whereas, if the area of contact is lesser, friction will be lesser and hence cone will not be stable.
Birthday cone image : Free image from- https://www.wallpaperflare.com/search?wallpaper=birthday+hat
Bicycle image : Image by Rudy and Peter Skitterians from Pixabay
Tricycle image: Wikimedia - https://upload.wikimedia.org/wikipedia/commons/0/01/Market_porter_pedals_jugaad_goods_carrier_tricycle_in_Thoothukudi%2C_Tamil_Nadu%2C_India.jpg