Terminology in the study design
Use of ‘force due to gravity’
For the purposes of the VCE Physics Study Design the force due to gravity will be referred to as Fg and no reference will be made to weight or weightlessness. The normal reaction force is referred to as FN and analyses of related motion will relate to these two forces.
Terminology for force, Fon A by B
Objects are often described as ‘having’ force or reference is sometimes made to the force ‘of’ an object. Such descriptions can lead to a misconception that if an object is moving it is because the object ‘has’ force. This misconception can exist in tandem with students knowing that if an object is moving at constant velocity then the forces on it are balanced.
This misconception may be dealt with by considering the momentum of an object in the first instance. An object that is moving ‘has’ momentum. If the momentum is changing then there is a force ‘acting on’ the object. The
VCE Physics Study Design considers the motion of an object in terms of the object and the forces acting ‘on’ it. Questions in physics generally require that students identify all of the forces acting ‘on’ an object. Consistent with this is the notation of describing the force ‘on’ an object ‘by’ a second object. Hence Fon A by B. The emphasis is on the object on which the forces are acting.
The accepted term for a force in the normal direction between two surfaces in contact is ‘normal force’. Teachers should note that the expressions ‘reaction force’ and ‘normal reaction force’ perpetuate misunderstandings in terms of the connection of the term ‘reaction’ to Newton’s third law. Firstly, the term ‘reaction’ in this law applies to force-pairs in all types of forces, not just the normal contact forces (so, friction along the direction of the plane of contact is an action-reaction force pair, but not normal to the plane). Second, there is no distinction about which of the pair of forces is the ‘action’ and which is the ‘reaction’. The term ‘reaction’ is validly used when carefully describing so-called ‘action-reaction’ force pairs in relation to Newton’s third law, and should be restricted to that usage.
Einstein’s special theory of relativity
The VCE Physics Study Design includes the study of Einstein’s special theory of relativity. Teachers should note that ‘special relativity’ is an abbreviation for Einstein’s special theory of relativity. Einstein’s theory of general relativity is beyond the scope of the
VCE Physics Study Design.