Friction (part-2)

FRICTION

Q.3. Suppose your writing desk is tilted a little. A book kept on it starts sliding down. Show the direction of frictional force acting on it.

Ans.3.

                               

Q.4. What is the cause of friction?
Ans.4. Friction occurs due to the interlocking of irregularities between two surfaces in motion to each other.

Every object has some sort of irregularities in its surface, so when two surfaces come in contact with each other and one object moves over the another, so their irregularities get interlocked and moving object starts losing its energy in breaking the interlocking and finally it comes to rest.

                                           

Q.5. What are the factors on which friction depends?
Ans.5. There are two factors affecting friction:

1.     Nature of the surfaces: Friction increases with roughness and decreases with smoothness of the surfaces. On rough surfaces, there are a larger number of irregularities than the smooth surfaces resulting in more interlocking and hence more friction than smooth surfaces.

2.     Weight of the object: Friction will increase if the two surfaces are pressed harder. The interlocking between two surfaces becomes more deeper and stronger with increase in weight of the object, hence Friction increases with increase in weight of the object.