Eduqas A-Level Physics A420QS
Basic Physics
Kinematics
Dynamics
Energy Concepts
Circular Motion
Vibrations
Kinetic Theory
Thermal Physics
Conduction of Electricity
Resistance
D.C. Circuits
Capacitance
Solids Under Stress
Electrostatic and Gravitational Fields of Force
Using Radiation to Investigate Stars
Orbits and the Wider Universe
The Nature of Waves
Wave Properties
Refraction of Light
Photons
Lasers
Nuclear Decay
Particles and Nuclear Structure
Nuclear Energy
Magnetic Fields
Electromagnetic Induction
Option A: Alternating CurrentsOption A
Option B: Medical PhysicsOption B
Option C: The Physics of SportsOption C
Option D: Energy and the EnvironmentOption D
Mathematical Requirements (Appendix C)
Vibrations
Energy in simple harmonic motion
- 3 things to know
- Component 1
Overview
Recall questions on the interchange between kinetic and potential energy through the cycle, where each is greatest and where zero, why the total stays constant in the absence of damping, and the shape of the energy against displacement graph.
What you need to know
Answer each one before you reveal it.
State the total energy of a simple harmonic oscillator in terms of its mass, angular frequency and amplitude.
State the total energy of a mass-spring oscillator in terms of the spring stiffness and the amplitude.
Questions from this subtopic
Each one with the model answer underneath.
- 1
Describe how the kinetic and potential energies of an undamped simple harmonic oscillator vary through one cycle.
Model answer
The energy is entirely potential at the two extremes and entirely kinetic at the equilibrium position, and the two interchange continuously while their sum stays constant.
- 2
State the total energy of a simple harmonic oscillator in terms of its mass, angular frequency and amplitude.
Model answer
The total energy is E = ½mω²A², where m is the mass in kg, ω the angular frequency in rad s⁻¹ and A the amplitude in m.
- 3
State the total energy of a mass-spring oscillator in terms of the spring stiffness and the amplitude.
Model answer
The total energy is E = ½kA², where k is the stiffness in N m⁻¹ and A the amplitude in m.
- 4
Write an expression for the kinetic energy of a simple harmonic oscillator at displacement x.
Model answer
The kinetic energy is Eₖ = ½mω²(A² − x²), which follows from ½mv² with v = ω√(A² − x²).
- 5
Write an expression for the potential energy of a simple harmonic oscillator at displacement x.
Model answer
The potential energy is Eₚ = ½mω²x². That expression is the total energy minus the kinetic energy at that displacement.
- 6
Describe the shape of a graph of potential energy against displacement for a simple harmonic oscillator.
Model answer
The graph is a parabola with its minimum at the origin, since the potential energy is proportional to the square of the displacement.
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