Define friction and write the factors …

There are ample of factors affecting friction. Some of them which are in my mind are listed below: 1. Nature of the surfaces in contact like hard or smooth. To understand this properly, you can perform one activity which I am going to tell you i.e:- Make an inclined plane using a cardboard supported with bricks. Mark a point A on any part of that cardboard. Let a pencil cell move down through this point. Now, spread a piece of cloth on the cardboard and repeat the same activity. After this you will observe that the pencil cell covered larger distance when moved on a cardboard as compared to piece of cloth. 2. How hard the two surfaces are compressed together. For example: If we are pushing a massive box which is at rest. There will be no doubt more interlocking of the molecular substances between two surfaces and henceby, we would apply more static friction in order to move that box. Now, if we would try to move a light box, there will be less interlocking of the molecules between two surfaces and henceforth, we would apply less static friction to move that box. Now, I hope that you clearly understood the factors affecting the friction. Thank you…

Friction force

• The external force that opposes relative motion between 2 surfaces in contact. 
• Friction acts on the surface of contact of both the bodies.

Factors affecting friction

Depends on the nature of surfaces in contact. (Friction exists between two surfaces) E.g.: glass and rubber

Nature of surface in contact

• Friction depends on how hard the two surfaces pressed together, as more surface in contact and more bonds are formed→ more bonds to break → means more friction.
• Only the normal reaction force (exactly perpendicular ) to the two surfaces increases friction.

Calculating frictional force using a spring balance

• Using a spring balance we can find the frictional forces opposed by different materials.
• Sandpaper gives a higher reading as compared to stainless steel.