Forces and equilibrium

Learning objectives

Draw a force diagram showing the weight, normal contact force, friction, tension, thrust and any applied force acting on a particle

Resolve forces into two perpendicular directions and find the magnitude and direction of the resultant of several forces

Use the condition that the components in any two perpendicular directions each sum to zero to find unknown forces and angles for a particle in equilibrium

Model a contact force as a normal component R and a frictional component F with F ≤ μR, taking F = μR when a particle is in limiting equilibrium or on the point of slipping

Explain what the models of a smooth surface and a light inextensible string assume, and use Newton's third law for the equal and opposite forces between objects in contact