Key term
OCR GCSE Combined Science Physics J250
Electricity
Topic overviewCharge, and producing static electricityTransfer of electrons in charging and dischargingCurrent as a rate of flow of chargeCharge, current and timeSeries and parallel circuits, and circuit symbolsCurrent, potential difference and resistanceResistors whose resistance changes, and investigating themLinear and non-linear circuit elements from graphsNet resistance in series and parallelCircuits for measurement, and electrical power
Energy
Topic overviewConservation of energy, and energy storesEnergy changes on heating, and calculating themEnergy of a moving body, a spring and a raised objectDissipation, and energy transfer in domestic devicesPower ratings, and calculating efficiencyReducing unwanted energy transfer, and the rate of cooling
Forces
Topic overviewMeasuring distance and time, and calculating speedConverting units, and ratesVectors and scalars in motionDistance-time and velocity-time graphsAverage speed, and the equations of uniform motionHow objects interact, and forces as vectorsNewton's first lawNewton's second lawWork done, and stored energyPower, and Newton's third lawStretching, bending and compressing; elastic and plasticForce and extension, linear and non-linearThe spring constant, and work done in stretchingGravitational fields, weight and free fallCalculations with weight and gravitational field strength
Global Challenges
Topic overviewTypical speeds and everyday accelerationsReaction time, stopping distance and the dangers of large decelerationsStopping distance, acceleration and collision force calculationsEnergy resources, and trends in their useThe national grid, and step-up and step-down transformersWhy the national grid is efficient, and power in a transformerMains electricity: a.c., d.c. and the domestic supplyLive, neutral and earth wires, and electrical danger
Magnetism and Magnetic Fields
Matter
Topic overviewHow the atomic model changed, and the structure of the atomThe size of atoms, and defining densityDensity of the states of matter, and density calculationsConservation of mass in changes of stateHeating a system, and specific heat capacityCalculations with specific heat capacity and latent heatGas molecules, temperature and pressure
Radioactivity
Waves in Matter
Topic overviewAmplitude, wavelength, frequency and periodThe wave equationTransverse and longitudinal wavesModelling waves with ripples and soundElectromagnetic waves as transverse, and energy transferFrequency and wavelength across the spectrumWhat our eyes detect, and light as an electromagnetic waveUses of electromagnetic wavesHazards of ultraviolet, X-rays and gamma raysInvestigating reflection and refraction of light
Forces
Distance-time and velocity-time graphs
- 3 things to know
- Paper 5 (Physics)
Overview
What horizontal, steeper and curving lines mean on a distance-time graph, what the gradient and horizontal or downward-sloping lines show on a velocity-time graph, calculating acceleration from the gradient, and describing a journey from its graph.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
On a distance–time graph, what does a horizontal line show?
Key term
On a distance–time graph, what does a steeper line mean?
Questions from this subtopic
Each one with the model answer underneath.
- 1
On a distance–time graph, what does a horizontal line show?
Model answer
The object is stationary, because its distance is not changing.
- 2
On a distance–time graph, what does a steeper line mean?
Model answer
The object is moving at a greater speed.
- 3
A distance–time graph curves upwards, getting steeper and steeper. What is happening to the motion?
Model answer
The object is speeding up, because the gradient and therefore the speed is increasing.
- 4
On a velocity–time graph, what does the gradient of the line represent?
Model answer
The acceleration of the object.
- 5
On a velocity–time graph, what does a horizontal line above the time axis show?
Model answer
The object is moving at a constant velocity.
- 6
A velocity–time graph slopes downwards towards the time axis. What is the object doing?
Model answer
It is slowing down, because its velocity is falling.
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