This resource is from a collection of Nuffield Maths resources exploring dynamics. The demand is roughly equivalent to that in GCE A level. The resources typically include slide shows to introduce the topics, student sheets and teacher notes, as well as other relevant resources.
This resource is a practical activity in which students investigate the relationship between the normal contact force and limiting friction. They should discover that friction is a variable force and its maximum value is proportional to the normal contact force.