*Learners should be able to demonstrate and apply their knowledge and understanding of:*

**3.1 Motion**

**3.1.1 Kinematics**

(a) displacement, instantaneous speed, average speed, velocity and acceleration

(b) graphical representations of displacement, speed, velocity and acceleration

(c) Displacement–time graphs; velocity is gradient

(d) Velocity–time graphs; acceleration is gradient; displacement is area under graph.

**3.1.2 Linear motion**

(a) (i) the equations of motion for constant acceleration in a straight line, including motion of bodies falling in a uniform gravitational field without air resistance

(ii) techniques and procedures used to investigate the motion and collisions of objects

(b) (i) acceleration g of free fall

(ii) techniques and procedures used to determine the acceleration of free fall using trapdoor and electromagnet arrangement or light gates and timer

(c) reaction time and thinking distance; braking distance and stopping distance for a vehicle.

**3.1.3 Projectile motion**

(a) independence of the vertical and horizontal motion of a projectile

(b) two-dimensional motion of a projectile with constant velocity in one direction and constant acceleration in a perpendicular direction.

**3.2 Forces in action **

**3.2.1 Dynamics**

(a) ;

(b) the newton as the unit of force

(c) weight of an object;

(d) the terms tension, normal contact force, upthrust and friction

(e) free-body diagrams

(f) one- and two-dimensional motion under constant force.

**3.2.2 Motion with non-uniform acceleration**

(a) drag as the frictional force experienced by an object travelling through a fluid

(b) factors affecting drag for an object travelling through air

(c) motion of objects falling in a uniform gravitational field in the presence of drag

(d) (i) terminal velocity

(ii) techniques and procedures used to determine terminal velocity in fluids.

**3.2.3 Equilibrium**

(a) moment of force

(b) couple; torque of a couple

(c) the principle of moments

(d) centre of mass; centre of gravity; experimental determination of centre of gravity

(e) equilibrium of an object under the action of forces and torques

(f) condition for equilibrium of three coplanar forces; triangle of forces

**3.2.4 Density and pressure**

(a) density;

(b) pressure; for solids, liquids and gases

(c) ; upthrust on an object in a fluid; Archimedes’ principle.

**3.3 Work, energy and power**

**3.3.1 Work and conservation of energy**

(a) work done by a force; the unit joule

(b) for work done by a force

(c) the principle of conservation of energy

(d) energy in different forms; transfer and conservation

(e) transfer of energy is equal to work done.

**3.3.2 Kinetic energy and potential energies**

(a) kinetic energy of an object;

(b) gravitational potential energy of an object in a uniform gravitational field;

(c) the exchange between gravitational potential energy and kinetic energy.

**3.3.3 Power**

(a) power; the unit watt;

(b)

(c) efficiency of a mechanical system;

**3.4 Materials**

**3.4.1 Springs**

(a) tensile and compressive deformation; extension and compression

(b) Hooke’s law

(c) force constant k of a spring or wire;

(d) (i) force–extension (or compression) graphs for springs and wires

(ii) techniques and procedures used to investigate force–extension characteristics for arrangements which may include springs, rubber bands, polythene strips.

**3.4.2 Mechanical properties of matter**

(a) force–extension (or compression) graph; work done is area under graph

(b) elastic potential energy; ;

(c) stress, strain and ultimate tensile strength

(d) (i) ,

(ii) techniques and procedures used to determine the Young modulus for a metal

(e) stress–strain graphs for typical ductile, brittle and polymeric materials

(f) elastic and plastic deformations of materials.

**3.5 Newton’s laws of motion and momentum**

**3.5.1 Newton’s laws of motion**

(a) Newton’s three laws of motion

(b) linear momentum; ; vector nature of momentum

(c) net force = rate of change of momentum;

(d) impulse of a force;

(e) impulse is equal to the area under a force–time graph.

**3.5.2 Collisions**

(a) the principle of conservation of momentum

(b) collisions and interaction of bodies in one dimension and in two dimensions

(c) perfectly elastic collision and inelastic collision.