Forces activity

We will conduct an experiment to investigate how the mass of an object sliding on the surface of a table influences the friction forces acting between the two surfaces. Complete the table below.
Mass
Experiment
Force required to overcome friction
100 grams
Click to see the experiment
200 grams
Click to see the experiment
50 grams
Click to see the experiment
Plot a graph of mass versus friction force below.

What will be the friction force if a mass of 75 grams is placed on the object?

A shoe manufacturer requires a friction force of 12 units so that the shoe does not slide. What is the minimum mass that should be placed on the shoe?
The same shoe manufacturer as in the question above requires tests to be conducted on three materials to determine the friction force each one generates with a special floor surface. Jonathon is a bright student who is given the task of designing the experiment. Below is the table of data he has prepared. Complete the table and determine which material generates the most friction force.
Experiment
Friction force (N)
Click to see the experiment for material "A"
Click to see the experiment for material "B"
Click to see the experiment for material "C"

What material generates the most friction force?

How accurate is the comparison of each material? What should be changed in the experimental design so that a more accurate comparison can be achieved?

Stephen suggests to Jonathon that the surface area of the shoe in contact with the floor also plays a part in determining the friction force. Jonathon is not convinced and so asks Stephen to design an experiment to determine the relationship between surface area and friction.

Design the experiment for Stephen.