1.Static - when the two objects in contact are not moving/at rest.
-pencil and the table , books and
the shelf , bag and the chair.
2.Sliding - occurs when the bumps and hallows on the surfaces of two materials resist against each other.
-pulling and pushing of the mouse of the computer , flat iron on the cloth during ironing.
3.Rolling - the force between a wheel or roller and the surface which it is in contact with.
-wheels of a car moving on the road , bowling balls rolling on the alley , skateboard played in the park.
