Calculation of fuel uses and costs in the domestic context
comparing energy values of different foods (from labels) (kJ)
comparing power ratings of appliances in watts (W, kW)
comparing amounts of energy transferred (J, kJ, kW hour)
domestic fuel bills, fuel use and costs
fuels and energy resources
Energy changes and transfers
simple machines give bigger force but at the expense of smaller movement (and vice versa): product of force and displacement unchanged
heating and thermal equilibrium: temperature difference between 2 objects leading to energy transfer from the hotter to the cooler one, through contact (conduction) or radiation; such transfers tending to reduce the temperature difference; use of insulators
other processes that involve energy transfer: changing motion, dropping an object, completing an electrical circuit, stretching a spring, metabolism of food, burning fuels
Changes in systems
energy as a quantity that can be quantified and calculated; the total energy has the same value before and after a change
comparing the starting with the final conditions of a system and describing increases and decreases in the amounts of energy associated with movements, temperatures, changes in positions in a field, in elastic distortions and in chemical compositions
using physical processes and mechanisms, rather than energy, to explain the intermediate steps that bring about such changes
Motion and forces
Describing motion
speed and the quantitative relationship between average speed, distance and time (speed = distance ÷ time)
the representation of a journey on a distance-time graph
relative motion: trains and cars passing one another
Forces
forces as pushes or pulls, arising from the interaction between 2 objects
using force arrows in diagrams, adding forces in 1 dimension, balanced and unbalanced forces
moment as the turning effect of a force
forces: associated with deforming objects; stretching and squashing – springs; with rubbing and friction between surfaces, with pushing things out of the way; resistance to motion of air and water
forces measured in newtons, measurements of stretch or compression as force is changed
force-extension linear relation; Hooke’s Law as a special case
work done and energy changes on deformation
non-contact forces: gravity forces acting at a distance on Earth and in space, forces between magnets, and forces due to static electricity
Pressure in fluids
atmospheric pressure, decreases with increase of height as weight of air above decreases with height
pressure in liquids, increasing with depth; upthrust effects, floating and sinking
pressure measured by ratio of force over area – acting normal to any surface
Balanced forces
opposing forces and equilibrium: weight held by stretched spring or supported on a compressed surface
Forces and motion
forces being needed to cause objects to stop or start moving, or to change their speed or direction of motion (qualitative only)
change depending on direction of force and its size
Waves
Observed waves
waves on water as undulations which travel through water with transverse motion; these waves can be reflected, and add or cancel – superposition
Sound waves
frequencies of sound waves, measured in hertz (Hz); echoes, reflection and absorption of sound
sound needs a medium to travel, the speed of sound in air, in water, in solids
sound produced by vibrations of objects, in loudspeakers, detected by their effects on microphone diaphragm and the ear drum; sound waves are longitudinal
the auditory range of humans and animals
Energy and waves
pressure waves transferring energy; use for cleaning and physiotherapy by ultrasound; waves transferring information for conversion to electrical signals by microphone
Light waves
the similarities and differences between light waves and waves in matter
light waves travelling through a vacuum; speed of light
the transmission of light through materials: absorption, diffuse scattering and specular reflection at a surface
use of ray model to explain imaging in mirrors, the pinhole camera, the refraction of light and action of convex lens in focusing (qualitative); the human eye
light transferring energy from source to absorber, leading to chemical and electrical effects; photosensitive material in the retina and in cameras
colours and the different frequencies of light, white light and prisms (qualitative only); differential colour effects in absorption and diffuse reflection
Electricity and electromagnetism
Current electricity
electric current, measured in amperes, in circuits, series and parallel circuits, currents add where branches meet and current as flow of charge
potential difference, measured in volts, battery and bulb ratings; resistance, measured in ohms, as the ratio of potential difference (p.d.) to current
differences in resistance between conducting and insulating components (quantitative)
Static electricity
separation of positive or negative charges when objects are rubbed together: transfer of electrons, forces between charged objects
the idea of electric field, forces acting across the space between objects not in contact
Magnetism
magnetic poles, attraction and repulsion
magnetic fields by plotting with compass, representation by field lines
Earth’s magnetism, compass and navigation
the magnetic effect of a current, electromagnets, DC motors (principles only)
Matter
Physical changes
conservation of material and of mass, and reversibility, in melting, freezing, evaporation, sublimation, condensation, dissolving
similarities and differences, including density differences, between solids, liquids and gases
Brownian motion in gases
diffusion in liquids and gases driven by differences in concentration
the difference between chemical and physical changes
Particle model
the differences in arrangements, in motion and in closeness of particles explaining changes of state, shape and density; the anomaly of ice-water transition
atoms and molecules as particles
Energy in matter
changes with temperature in motion and spacing of particles
internal energy stored in materials
Space physics
gravity force, weight = mass x gravitational field strength (g), on Earth g=10 N/kg, different on other planets and stars; gravity forces between Earth and Moon, and between Earth and sun (qualitative only)
our sun as a star, other stars in our galaxy, other galaxies
the seasons and the Earth’s tilt, day length at different times of year, in different hemispheres
Calculation of fuel uses and costs in the domestic context
energy changes in a system involving heating, doing work using forces, or doing work using an electric current: calculating the stored energies and energy changes involved
conservation of energy in a closed system, dissipation
calculating energy efficiency for any energy transfers
renewable and non-renewable energy sources used on Earth, changes in how these are used
Forces
forces and fields: electrostatic, magnetic, gravity
forces as vectors
calculating work done as force x distance; elastic and inelastic stretching
pressure in fluids acts in all directions: variation in Earth’s atmosphere with height, with depth for liquids, up-thrust force (qualitative)
Forces and motion
speed of sound, estimating speeds and accelerations in everyday contexts
interpreting quantitatively graphs of distance, time, and speed
acceleration caused by forces; Newton’s First Law
weight and gravitational field strength
decelerations and braking distances involved on roads, safety
Wave motion
amplitude, wavelength, frequency, relating velocity to frequency and wavelength
transverse and longitudinal waves
electromagnetic waves, velocity in vacuum; waves transferring energy; wavelengths and frequencies from radio to gamma-rays
velocities differing between media: absorption, reflection, refraction effects
production and detection, by electrical circuits, or by changes in atoms and nuclei
uses in the radio, microwave, infra-red, visible, ultra-violet, X-ray and gamma-ray regions, hazardous effects on bodily tissues
Electricity
measuring resistance using p.d. and current measurements
exploring current, resistance and voltage relationships for different circuit elements; including their graphical representations
quantity of charge flowing as the product of current and time
drawing circuit diagrams; exploring equivalent resistance for resistors in series
the domestic a.c. supply; live, neutral and earth mains wires, safety measures
power transfer related to p.d. and current, or current and resistance
Magnetism and electromagnetism
exploring the magnetic fields of permanent and induced magnets, and the Earth’s magnetic field, using a compass
magnetic effects of currents, how solenoids enhance the effect
how transformers are used in the national grid and the reasons for their use
The structure of matter
relating models of arrangements and motions of the molecules in solid, liquid and gas phases to their densities
melting, evaporation, and sublimation as reversible changes
calculating energy changes involved on heating, using specific heat capacity; and those involved in changes of state, using specific latent heat
links between pressure and temperature of a gas at constant volume, related to the motion of its particles (qualitative)
Atomic structure
the nuclear model and its development in the light of changing evidence
masses and sizes of nuclei, atoms and small molecules
differences in numbers of protons, and neutrons related to masses and identities of nuclei, isotope characteristics and equations to represent changes
ionisation; absorption or emission of radiation related to changes in electron orbits
radioactive nuclei: emission of alpha or beta particles, neutrons, or gamma-rays, related to changes in the nuclear mass and/or charge
radioactive materials, half-life, irradiation, contamination and their associated hazardous effects, waste disposal
nuclear fission, nuclear fusion and our sun’s energy