OCR A Level Physics A Module 5: Newtonian World and Astrophysics Exam Questions

About OCR A Level Physics A Module 5: Newtonian World and Astrophysics

Module 5 of OCR A Level Physics A, Newtonian World and Astrophysics, extends the mechanics of Module 3 to thermal physics, circular and oscillatory motion, gravitation and the universe. It covers temperature, specific heat and latent heat, ideal gases and kinetic theory, circular motion, simple harmonic motion and resonance, gravitational fields and Kepler's laws, the life cycle of stars, Hertzsprung-Russell diagrams, energy levels and spectra, and Hubble's law and the Big Bang. Examiners regularly set specific heat capacity practicals, SHM equation and graph questions, orbital period calculations, Wien's and Stefan's law problems, and questions on the evidence for the expanding universe.

What you need to know

• 5.1 Thermal equilibrium, absolute zero, internal energy, specific heat capacity E = mc Delta theta, specific latent heat E = mL, ideal gas equations pV = nRT and pV = NkT, and pV = 1/3 N m c^2 with mean kinetic energy 3/2 kT.
• 5.2 The radian, angular velocity, centripetal acceleration a = v^2 / r = omega^2 r and centripetal force.
• 5.3-5.4 SHM with a = -omega^2 x, displacement and velocity equations, energy in SHM, damping, forced oscillations and resonance; gravitational field strength, Newton's law of gravitation, gravitational potential and energy, Kepler's laws, geostationary orbits and escape velocity.
• 5.5 Star formation and evolution, the HR diagram, energy levels and spectra, Wien's law and Stefan's law, stellar distances using parallax, the Doppler effect, Hubble's law, the Big Bang, the cosmic microwave background and dark matter and dark energy.

Common mistakes in Module 5: Newtonian World and Astrophysics

• Using degrees instead of radians in SHM and circular motion equations. Use radians and check your calculator mode.
• Writing that temperature rises during a change of state. Energy supplied during melting or boiling increases internal potential energy, so temperature stays constant.
• Saying gravitational potential is zero at the Earth's surface. It is zero at infinity and negative everywhere else.
• Thinking a geostationary satellite can orbit at any height. It must have a 24 hour period, which fixes its orbital radius, and be above the equator.
• Describing redshift as stars moving away through space only. Cosmological redshift is due to the expansion of space itself stretching wavelengths.

Try three Module 5: Newtonian World and Astrophysics exam-style questions