What is the difference between sliding and rolling of a wheel?

[teng125]

can anyone pls explain to me what is sliding and rolling of a let say a wheel??I'm really confuse about it
thanx

 

[arildno]

Ok:
Imagine a surface wetted with paint, and place a moving wheel upon it.
Now, there are two extremes that may happen:

1) The wheel is merely rotating, but its center is at rest.
Thus, gradually, the whole rim of the wheel gets painted, but on the SURFACE, paint is only removed from a SINGLE point (the contact point).

We say that the wheel is SPINNING.

2) The wheel moves forward, but the only point on the wheel that gets painted is the one point always in contact with the surface.
On the SURFACE, a line is traced out in the paint.

We say that the wheel is SLIDING.

And then:
With ROLLING, we mean that the arc painted onto the wheel is always of equal length as the line traced out on the wetted surface.

 

[teng125]

ok.thanx...