# Equilibrium of a rigid body – Further Mechanics Paper 3

Candidates should be able to:

• calculate the moment of a force about a point (For questions involving coplanar forces only; understanding of the vector nature of moments is not required.)
• use the result that the effect of gravity on a rigid body is equivalent to a single force acting at the centre of mass of the body, and identify the position of the centre of mass of a uniform body using considerations of symmetry
• use given information about the position of the centre of mass of a triangular lamina and other simple shapes (Proofs of results given in the MF19 List of formulae are not required.)
• determine the position of the centre of mass of a composite body by considering an equivalent system of particles (Simple cases only, e.g. a uniform L-shaped lamina, or a uniform cone joined at its base to a uniform hemisphere of the same radius.)
• use the principle that if a rigid body is in equilibrium under the action of coplanar forces then the vector sum of the forces is zero and the sum of the moments of the forces about any point is zero, and the converse of this
• solve problems involving the equilibrium of a single rigid body under the action of coplanar forces, including those involving toppling or sliding.

Equilibrium of a rigid body – Further Mechanics Paper 3 Videos 3 Parts

• Moments (7 videos)
• Centre of Gravity and Centre of Mass (6 videos)
• Sliding & Toppling (7 videos)