Module 2: Dynamics

Outcomes

A student:

• designs and evaluates investigations in order to obtain primary and secondary data and
  information PH11/12-2
• selects and processes appropriate qualitative and quantitative data and information using a range
  of appropriate media PH11/12-4
• solves scientific problems using primary and secondary data, critical thinking skills and scientific
  processes PH11/12-6
• describes and explains events in terms of Newton’s Laws of Motion, the law of conservation of
  momentum and the law of conservation of energy PH11-9

Content Focus

The relationship between the motion of objects and the forces that act on them is often complex.
However, Newton’s Laws of Motion can be used to describe the effect of forces on the motion of
single objects and simple systems. This module develops the key concept that forces are always
produced in pairs that act on different objects and add to zero.
By applying Newton’s laws directly to simple systems, and, where appropriate, the law of
conservation of momentum and law of conservation of mechanical energy, students examine the
effects of forces. They also examine the interactions and relationships that can occur between objects
by modelling and representing these using vectors and equations.
In many situations, within and beyond the discipline of physics, knowing the rates of change of
quantities provides deeper insight into various phenomena. In this module, the rates of change of
displacement, velocity and energy are of particular significance and students develop an
understanding of the usefulness and limitations of modelling.

Working Scientifically

In this module, students focus on designing, evaluating and conducting investigations and interpreting
trends in data to solve problems related to dynamics. Students should be provided with opportunities
to engage with all the Working Scientifically skills throughout the course.

Content

Forces

Inquiry question: How are forces produced between objects and what effects do forces produce?
Students:

• using Newton’s Laws of Motion, describe static and dynamic interactions between two or more
  objects and the changes that result from:
  •  a contact force
  • a force mediated by fields
• explore the concept of net force and equilibrium in one-dimensional and simple two-dimensional
  contexts using: (ACSPH050)
  • algebraic addition
  • vector addition
  • vector addition by resolution into components
• solve problems or make quantitative predictions about resultant and component forces by
  applying the following relationships:
  • 
  • 
  • , 
• conduct a practical investigation to explain and predict the motion of objects on inclined planes
  (ACSPH098)

Forces, Acceleration and Energy

Inquiry question: How can the motion of objects be explained and analysed?

Students:

• apply Newton’s first two laws of motion to a variety of everyday situations, including both static
  and dynamic examples, and include the role played by friction  (ACSPH063)
• investigate, describe and analyse the acceleration of a single object subjected to a constant net
  force and relate the motion of the object to Newton’s Second Law of Motion through the use of:
  (ACSPH062, ACSPH063)
  • qualitative descriptions
  • graphs and vectors
  • deriving relationships from graphical representations including and relationships of uniformly accelerated motion
• apply the special case of conservation of mechanical energy to the quantitative analysis of motion
  involving:
  • work done and change in the kinetic energy of an object undergoing accelerated rectilinear
    motion in one dimension
  • changes in gravitational potential energy of an object in a uniform field
• conduct investigations over a range of mechanical processes to analyse qualitatively and
  quantitatively the concept of average power , , including but not
  limited to:
  • uniformly accelerated rectilinear motion
  • objects raised against the force of gravity
  • work done against air resistance, rolling resistance and friction

Momentum, Energy and Simple Systems

Inquiry question: How is the motion of objects in a simple system dependent on the interaction
between the objects?

Students:

• conduct an investigation to describe and analyse one-dimensional (collinear) and two-dimensional
  interactions of objects in simple closed systems (ACSPH064)
• analyse quantitatively and predict, using the law of conservation of momentum  and, where appropriate, conservation of kinetic energy , the results of interactions in elastic collisions (ACSPH066)
• investigate the relationship and analyse information obtained from graphical representations of
  force as a function of time
• evaluate the effects of forces involved in collisions and other interactions, and analyse
  quantitatively the interactions using the concept of impulse
• analyse and compare the momentum and kinetic energy of elastic and inelastic collisions