What you’ll learn7 learning objectivesChoose one objective for a focused lesson, or study the complete topic.4.1.1Forces• identify the forces acting in a given situation e.g. by drawing a force diagram.Syllabus objective4.1.2The vector nature of force• understand the vector nature of force, and find and use components and resultants Calculations are always required, not approximate solutions by scale drawing.Syllabus objective4.1.3Forces• use the principle that, when a particle is in equilibrium, the vector sum of the forces acting is zero, or equivalently, that the sum of the components in any direction is zero Solutions by resolving are usually expected, but equivalent methods (e.g. triangle of forces, Lami's Theorem, where suitable) are also acceptable; these other methods are not required knowledge, and will not be referred to in questions.Syllabus objective4.1.4Friction• understand that a contact force between two surfaces can be represented by two components, the normal component and the frictional componentSyllabus objective4.1.5The model of a 'smooth' contact• use the model of a 'smooth' contact, and understand the limitations of this modelSyllabus objective4.1.6Equilibrium• understand the concepts of limiting friction and limiting equilibrium, recall the definition of coefficient of friction, and use the relationship FR n= or FRG n, as appropriate Terminology such as 'about to slip' may be used to mean 'in limiting equilibrium' in questions.Syllabus objective4.1.7Newton's laws• use Newton's third law. e.g. the force exerted by a particle on the ground is equal and opposite to the force exerted by the ground on the particle.Syllabus objective