Principle

Using a friction block, the students should establish that
the frictional force is independent of the surface area.
For a constant surface area the students should vary the mass of
the friction block and measure the frictional force Fr in each
case. A graph of these results should then be investigated, showing
clearly the proportionality between frictional force and weight
(force). Finally, the students should also calculate the
coefficient of friction, μ, from the slope of the straight
line.