Unit 5: Thermodynamics, Radiation, Oscillations and Cosmology

Be able to use the equations ΔE = mcΔθ and ΔE = LΔm

CORE PRACTICAL 12: Calibrate a thermistor in a potential divider circuit as a thermostat

CORE PRACTICAL 13: Determine the specific latent heat of a phase change

Understand the concept of internal energy as the random distribution of potential and kinetic energy amongst molecules

Understand the concept of absolute zero and how the average kinetic energy of molecules is related to the absolute temperature

Be able to use the equation pV = NkT for an ideal gas

CORE PRACTICAL 14: Investigate the relationship between pressure and volume of a gas at fixed temperature

Derive and use ½m⟨c²⟩ = 3kT/2 for molecular kinetic theory.

Understand the concept of nuclear binding energy and be able to use the equation ΔE = c2Δm in calculations of nuclear mass (including mass deficit) and energy

Use the atomic mass unit (u) to express small masses and convert between this and SI units

Understand the processes of nuclear fusion and fission with reference to the binding energy per nucleon curve

Understand the mechanism of nuclear fusion and the need for very high densities of matter and very high temperatures to bring about and maintain nuclear fusion

Understand that there is background radiation and how to take appropriate account of it in calculations

Understand the relationships between the nature, penetration, ionising ability and range in different materials of nuclear radiations (alpha, beta and gamma)

Be able to write and interpret nuclear equations given the relevant particle symbols

CORE PRACTICAL 15: Investigate the absorption of gamma radiation by lead

Understand the spontaneous and random nature of nuclear decay

Determine half-life graphically and use A = λN, dN/dt = −λN, λ = ln 2/t½, N = N0e^(−λt), and A = A0e^(−λt), including the corresponding logarithmic equations.

Understand that the condition for simple harmonic motion is F = − kx, and hence understand how to identify situations in which simple harmonic motion will occur

Use a = −ω²x, x = A cos ωt, v = −Aω sin ωt, a = −Aω² cos ωt, T = 1/f = 2π/ω, and ω = 2πf for simple harmonic motion.

Use T = 2π√(m/k) for a mass–spring oscillator and T = 2π√(l/g) for a simple pendulum.

Be able to draw and interpret a displacement-time graph for an object oscillating and know that the gradient at a point gives the velocity at that point

Be able to draw and interpret a velocity-time graph for an oscillating object and know that the gradient at a point gives the acceleration at that point

Understand what is meant by resonance

CORE PRACTICAL 16: Determine the value of an unknown mass using the resonant frequencies of the oscillation of known masses

Understand how to apply conservation of energy to damped and undamped oscillating systems

Understand the distinction between free and forced oscillations

Understand how the amplitude of a forced oscillation changes at and around the natural frequency of a system and know, qualitatively, how damping affects resonance

Understand how damping and the plastic deformation of ductile materials reduce the amplitude of oscillation.

5.6.154Gravitational fields

Understand that a gravitational field is a region where a mass experiences a force.

5.6.155Gravitational field strength

Understand gravitational field strength g = F/m and use this relationship.

5.6.156Newton’s law of universal gravitation

Use Newton's law of gravitation F = Gm1m2/r².

5.6.157Gravitational field due to a point mass

Derive and use g = Gm/r² for the gravitational field due to a point mass.

5.6.158Gravitational potential in a radial field

Use Vgrav = −Gm/r for gravitational potential in a radial field.

5.6.159Electric and gravitational fields comparison

Be able to compare electric fields with gravitational fields

5.6.160Orbital motion

Be able to apply Newton’s laws of motion and universal gravitation to orbital motion

5.6.161Black body radiation curves

Understand what is meant by a black body radiator and be able to interpret radiation curves for such a radiator

5.6.162Stefan-Boltzmann law

Be able to use the Stefan-Boltzmann law equation L = σAT4 for black body radiators

5.6.163Wien’s law

Use Wien's law λmaxT = 2.898 × 10^−3 m K for black-body radiators.

5.6.164Radiation intensity from luminosity and distance

Use radiation intensity I = L/(4πd²), where L is luminosity and d is distance from the source.

5.6.165Distance by trigonometric parallax

Understand how astronomical distances can be determined using trigonometric parallax

5.6.166Distance by standard candles

Understand how astronomical distances can be determined using measurements of intensity received from standard candles (objects of known luminosity)

5.6.167Hertzsprung-Russell diagram

Be able to sketch and interpret a simple Hertzsprung-Russell diagram that relates stellar luminosity to surface temperature

5.6.168Hertzsprung-Russell diagram and stellar life cycles

Understand how to relate the Hertzsprung-Russell diagram to the life cycle of stars

5.6.169Doppler effect

Understand how the movement of a source of waves relative to an observer/detector gives rise to a shift in frequency (Doppler effect)

5.6.170Redshift and Hubble’s law

Use redshift z = Δλ/λ ≈ −Δf/f ≈ v/c for a source moving relative to an observer, and Hubble's law v = H0d for cosmological distances.

5.6.171Age and fate of the universe

Understand the controversy over the age and ultimate fate of the universe associated with the value of the Hubble constant and the possible existence of dark matter.