Describe, with examples, how objects can interact

a) at a distance without contact, linking these to the gravitational, electrostatic and magnetic fields involved
b) by contact, including normal contact force and friction
c) producing pairs of forces which can be represented as vectors

Explain the difference between vector and scalar quantities using examples

Use vector diagrams to illustrate resolution of forces, a net force, and equilibrium situations (scale drawings only)

Draw and use free body force diagrams

Explain examples of the forces acting on an isolated solid object or a system where several forces lead to a resultant force on an object and the special case of balanced forces when the resultant force is zero

Describe situations where forces can cause rotation

Recall and use the equation:

moment of a force (newton metre, Nm) = force (newton, N) × distance normal to the direction of the force (metre, m)

Recall and use the principle of moments in situations where rotational forces are in equilibrium:

the sum of clockwise moments = the sum of anti-clockwise moments

for rotational forces in equilibrium

Explain how levers and gears transmit the rotational effects of forces

Explain ways of reducing unwanted energy transfer through lubrication