What are the two main causes of friction?

Answer 1

There are two types of friction: static friction and kinetic friction.

Static friction is the type of friction that keeps an object from moving, even when a force is acting upon it. For example, if you try to push a 1 billion kg block, you won't move it at all because of static friction. Or take a block on a slightly inclined table. Static friction allows the block to stay in place on a slightly inclined table.

Kinetic friction is the type of friction that takes place while the object is moving such as when you are pushing the vacuum around on a thick carpet.

It is important to note that the force of friction, even for the same object, is usually different for both static and kinetic friction.

Answer 2

Static friction, which is the friction that needs to be overcome to get an object moving ( different values on different surfaces ), and kinetic friction, which is the friction imparted to the object as it mover along ( different values for different surfaces ).

Answer 3

It's more complicated than "two causes."

Generally speaking rough surfaces have more friction then smooth. Think of sandpaper (rough) versus glass (smooth).

Generally speaking the more force holding the two surfaces together the more friction. Think of dragging a 5kg bicycle along the road behind you on a rope, versus an upside down 1500kg car on the same road...

But smooth surfaces can have high friction if they are soft.

Rubber is smooth but soft, in car tyres it gives better friction than a hard metal wheel would.

Some VERY VERY smooth and flat surfaces can have high friction even if they are hard. Polish metal/steel well enough, and get it flat enough, and clean enough, and it will join onto an identically flat/polished/clean bit if steel and become one, fusing the two together in a few minutes. The amount of work required to achieve this result means it is not worth the effort.

This ignores the application of lubricants. Racing cars can go round a track at high speeds on smooth rubber tyres, but add a bit of water, and they all slide off & crash.

Answer 4

The two main causes of friction are surface roughness and the force pushing the surfaces together. Surface roughness creates interlocking jagged edges that resist motion, while the force pushing the surfaces together creates contact forces that oppose the sliding motion.

Answer 5

the two types of friction are static and grate.

Answer 6

kinetic and static

Answer 7

Static and kinetic

Answer 8

static friction and kinetic friction

Answer 9

static