Unit 2: Linear motion and waves
14 dot points across 4 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.
Topic 1: Linear motion and force
- Recall, describe and apply the concepts of position, displacement, distance, speed, velocity and acceleration, distinguishing between scalar and vector quantities and between average and instantaneous values
A focused answer to the QCE Physics Unit 2 dot point on the basic kinematic quantities. Defines position, displacement, distance, speed, velocity and acceleration; distinguishes average and instantaneous values; and works the QCAA short-answer style problem on average versus instantaneous velocity that recurs in IA1 and the EA.
6 min answer → - Define linear momentum and impulse, and apply the principle of conservation of momentum to one-dimensional collisions and explosions, distinguishing between elastic and inelastic collisions
A focused answer to the QCE Physics Unit 2 dot point on momentum and impulse. Defines $p = mv$ and $J = F \Delta t = \Delta p$, walks through conservation of momentum in one-dimensional collisions and explosions, and distinguishes elastic from inelastic by whether kinetic energy is conserved. Works the QCAA two-cart collision standard problem.
7 min answer → - Analyse the linear motion of an object using graphs of position, velocity and acceleration against time, interpreting slope and area under the graph
A focused answer to the QCE Physics Unit 2 dot point on motion graphs. Reads slope and area on position-time, velocity-time and acceleration-time graphs; converts between them; and works the QCAA-style multi-phase journey problem that recurs in IA1 stimulus and EA Paper 1.
7 min answer → - Recall, describe and apply Newton's three laws of motion, including the use of free-body diagrams to identify forces acting on an object and solve problems involving weight, normal force, friction and tension
A focused answer to the QCE Physics Unit 2 dot point on Newton's three laws and force analysis. States each law, walks through free-body diagrams for the standard QCAA problem types (level surface with friction, inclined plane, connected bodies, hanging tension), and works a force-on-an-incline example that recurs in IA1 stimulus and EA Paper 2.
8 min answer → - Define power as the rate of doing work or transferring energy, and apply $P = W / t = Fv$ to mechanical systems, including efficiency calculations
A focused answer to the QCE Physics Unit 2 dot point on power and efficiency. Defines $P = W/t = Fv$, derives the relationship between power and velocity for a constant force, defines efficiency as useful energy out divided by total energy in, and works the QCAA-style elevator and motor problems used in EA Paper 1.
6 min answer → - Distinguish between scalar and vector quantities, including identifying examples and applying operations of addition and subtraction in one and two dimensions
A focused answer to the QCE Physics Unit 2 dot point on scalar and vector quantities. Defines the distinction with examples, walks through vector addition (head-to-tail and component methods), subtraction as adding the opposite, and the standard QCAA component resolution students use throughout Unit 2 motion and Unit 3 fields.
6 min answer → - Recall and apply the equations for uniformly accelerated motion to one-dimensional problems, including problems involving free fall under gravity
A focused answer to the QCE Physics Unit 2 dot point on the equations of uniformly accelerated motion. Lists the four QCAA-formulae-sheet suvat equations, the conditions under which they apply, and works the free-fall standard question that recurs in IA1 and EA Paper 1.
7 min answer → - Define work, kinetic energy and gravitational potential energy, and apply the principle of conservation of mechanical energy to one-dimensional problems including those with friction
A focused answer to the QCE Physics Unit 2 dot point on work and mechanical energy. Defines $W = Fs\cos\theta$, $KE = \frac{1}{2}mv^2$, $PE_g = mgh$, the work-energy theorem and conservation of mechanical energy; works the QCAA roller-coaster style problem including a friction case for the EA.
7 min answer →
How is linear motion analysed using Newton's laws?
Topic 2: Waves
- Explain the formation of standing waves in strings (fixed at both ends) and in air columns (open and closed pipes), and solve problems involving the resonant frequencies of mechanical systems
A focused answer to the QCE Physics Unit 2 dot point on standing waves and resonance. Derives the resonant-frequency series for a string fixed at both ends, an open pipe (both ends open) and a closed pipe (one end closed), and works the QCAA-style guitar-string and organ-pipe problems from EA Paper 1 and Paper 2.
7 min answer → - Describe the superposition of mechanical waves and explain constructive and destructive interference in terms of phase relationships
A focused answer to the QCE Physics Unit 2 dot point on superposition and interference. States the principle of superposition, links constructive and destructive interference to path-length difference and phase, and works the QCAA-style two-speaker interference problem from EA Paper 2.
6 min answer → - Recall and apply the wave equation $v = f \lambda$ to determine the speed, frequency or wavelength of a wave, including across media in which the wave speed changes
A focused answer to the QCE Physics Unit 2 dot point on the wave equation $v = f \lambda$. Reviews the algebra, applies it across mechanical and electromagnetic waves, and works the QCAA-style question on what happens to wavelength when a wave passes from one medium to another (frequency unchanged, speed and wavelength scale together).
6 min answer → - Describe mechanical waves as transverse or longitudinal, identifying their characteristics including wavelength, period, frequency, amplitude and speed, and giving examples of each
A focused answer to the QCE Physics Unit 2 dot point on the properties and types of mechanical waves. Defines wavelength, period, frequency, amplitude and speed, distinguishes transverse (string, water surface, electromagnetic) from longitudinal (sound, P-waves) and works the QCAA-style identification question that recurs in EA Paper 1 multiple choice.
6 min answer →