Question

Which of the following factors affect friction?
A. Nature of surface
B. Weight of object placed over other
C. Amount of surface area in contact between the moving bodies
D. Both A and B

Answer 1

Hint: in this question, we will write the factors on which friction depends, that are, the nature of the two surfaces in touch, either smooth or rough, and how strongly two surfaces between which friction is occurring are attached or what is the weight of the objects.

Step-By-Step answer:
The various factors which affect the friction are as follows
1. The first and foremost is the nature of the surfaces in touch, that is whether it is rough or smooth.
For example, we have seen that it is very easy to walk on a dry floor because it is rough in nature and will have more interlocking between the surfaces. But if we pour some water on the floor it will fill up space which helps in interlocking and Hence, we will start to slide or slip on the floor because the floor is smooth.

2. Secondly, friction depends on how strongly the surfaces are attached to one another which in turn depends on Normal force between the surfaces. Now we know that normal forces are dependent on the weight of the object. Therefore when we try to slide a heavy body over a surface there will be more interlocking between two surfaces due to the weight and hence, we would need to apply more force to slide that body. However, it is very easy to side a lighter body because its weight is less hence less interlocking between the surfaces.

3. Friction never depends on the amount of surface area of contact between the two bodies or objects.
Therefore option D is correct that is both options A and B are correct.

Note: For these types of questions we need to have a knowledge of different kinds of forces like frictional forces, air friction, the force due to tension, the force due to acceleration, force to gravity, and weight. We also need to know what factors they depend on and how to use these forces.