Unit 4: Further Mechanics, Fields and Particles

Understand how to use the equation impulse = F∆t =∆p (Newton’s second law of motion)

CORE PRACTICAL 9: Investigate the relationship between the force exerted on an object and its change of momentum

Understand how to apply conservation of linear momentum to problems in two dimensions

CORE PRACTICAL 10: Use ICT to analyse collisions between small spheres, e.g. ball bearings on a table top

Determine whether a collision is elastic or inelastic.

Derive and use Ek = p²/(2m) for the kinetic energy of a non-relativistic particle.

Be able to express angular displacement in radians and in degrees, and convert between these units

Understand angular velocity and use v = ωr and T = 2π/ω.

Use vector diagrams to derive centripetal acceleration a = v²/r = rω² and apply these equations.

Understand that a resultant centripetal force is required to produce and maintain circular motion.

Use centripetal force F = ma = mv²/r = mrω².

Understand that an electric field is a region where a charged particle experiences a force.

Understand electric field strength E = F/Q and use this relationship.

Use Coulomb's law F = Q1Q2/(4πε0r²) for the force between two point charges.

Use E = Q/(4πε0r²) for the electric field due to a point charge.

Know and understand the relationship between electric field and electric potential.

Use E = V/d for a uniform electric field between parallel plates.

Use V = Q/(4πε0r) for electric potential in a radial field.

Draw and interpret field-line and equipotential diagrams for radial and uniform electric fields.

Understand capacitance C = Q/V and use this relationship.

Use W = ½QV for capacitor energy, derive it from the area under a potential-difference–charge graph, and derive and use W = ½CV² and W = Q²/(2C).

Be able to draw and interpret charge and discharge curves for resistor capacitor circuits and understand the significance of the time constant RC

CORE PRACTICAL 11: Use an oscilloscope or data logger to display and analyse the potential difference (p.d.) across a capacitor as it charges and discharges through a resistor

Use Q = Q0e^(−t/RC), I = I0e^(−t/RC), and V = V0e^(−t/RC) for capacitor discharge, and derive and use ln Q = ln Q0 − t/RC, ln I = ln I0 − t/RC, and ln V = ln V0 − t/RC.

Understand and use the terms magnetic flux density B, flux φ and flux linkage Nφ

Be able to use the equation F = Bqv sinθ and apply Fleming’s left-hand rule to charged particles moving in a magnetic field

Be able to use the equation F = BIl sinθ and apply Fleming’s left-hand rule to current carrying conductors in a magnetic field

Understand the factors affecting the e.m.f. induced in a coil when there is relative motion between the coil and a permanent magnet

Understand the factors affecting the e.m.f. induced in a coil when there is a change of current in another coil linked with this coil

Use Faraday's law to determine induced e.m.f. and use the combined Faraday–Lenz equation ε = −d(NΦ)/dt.

4.5.111Nucleon number and proton number

Understand what is meant by nucleon number (mass number) and proton number (atomic number)

4.5.112Alpha scattering and the nuclear atom

Understand how large-angle alpha particle scattering gives evidence for a nuclear model of the atom and how our understanding of atomic structure has changed over time

4.5.113Thermionic emission and acceleration

Understand that electrons are released in the process of thermionic emission and how they can be accelerated by electric and magnetic fields

4.5.114Fields in particle accelerators and detectors

Understand the role of electric and magnetic fields in particle accelerators, including linacs and cyclotrons, and in detectors through ionisation and deflection.

4.5.115Charged-particle radius in a magnetic field

Derive and use r = mv/(BQ) for the radius of a charged particle moving perpendicular to a magnetic field.

4.5.116Particle interaction conservation laws

Be able to apply conservation of charge, energy and momentum to interactions between particles and interpret particle tracks

4.5.117High energies and nucleon structure

Understand why high energies are required to investigate the structure of nucleons

4.5.118Mass-energy equivalence

Be able to use the equation ∆E = c2∆m in situations involving the creation and annihilation of matter and antimatter particles

4.5.119Particle energy and mass units

Be able to use MeV and GeV (energy) and MeV/c2, GeV/c2 (mass) and convert between these and SI units

4.5.120Relativistic lifetime increase

Understand situations in which the relativistic increase in particle lifetime is significant (use of relativistic equations not required)

4.5.121Standard quark-lepton model

Know that in the standard quark-lepton model particles can be classified as: • baryons (e.g. neutrons and protons), which are made from three quarks • mesons (e.g. pions), which are made from a quark and an antiquark • leptons (e.g. electrons and neutrinos), which are fundamental particles • photons and that the symmetry of the model predicted the top quark

4.5.122Particles and antiparticles

Know that every particle has a corresponding antiparticle and be able to use the properties of a particle to deduce the properties of its antiparticle and vice versa

4.5.123Charge, baryon and lepton number conservation

Understand how to use laws of conservation of charge, baryon number and lepton number to determine whether a particle interaction is possible

4.5.124Particle equations

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