# Analysis of weight and its relationships

1. Dec 22, 2014

### HiDanny

1. The problem statement, all variables and given/known data
1. Explain in details in one paragraph (without using formulas) what effect the weight of a block has on the normal force, frictional force, and coefficient of friction. How would you increase or decrease the coefficient of friction?

2. Relevant equations
Give me any criticisms please. This is homework to check our understanding... Sorry :(

3. The attempt at a solution
On this horizontal surface, the effect of the weight of the block is that normal force equals weight. This is because normal force prevents the block from penetrating the table with gravity by negating weight, thus it equals to weight as it pushes the force of gravity on the block perpendicular to it. Since frictional force is directly proportional to normal force and that normal force equals weight, weight is directly proportional to frictional force. Therefore, with greater weight, there would be a greater force of friction or with lower weight, there would be a lower force of friction. Since normal force is directly proportional to weight and the coefficient of friction is indirectly proportional to the normal force, weight plays a large role in the magnitude of the coefficient of friction. To increase the coefficient of friction, we would have to change the surface that the block slides on. With a rougher surface, the block would experience a greater force of friction, thus a greater coefficient of friction as the coefficient of friction is proportional to the force of friction. To decrease the coefficient of friction, we would have to use a smoother surface for the wooden block to slide on as there would be a smaller of force of friction, leading to a lower coefficient of friction.

2. Dec 22, 2014

### haruspex

No. Frictional force is the actual force resulting from friction in a given situation. The maximum magnitude of the force is proportional to the normal force.
A block at rest on a horizontal surface, nothing else going on, experiences no frictional force.