Process
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, efficiency, and increasing itReducing 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 lawResolving forces, and free body diagramsResultant forces, and balanced forcesNewton's second law, and inertiaMomentum and its conservationWork done, and stored energyPower, and Newton's third lawCircular motion and changing velocityStretching, 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 raysProducing and receiving radio wavesAbsorption, transmission, refraction and reflectionInvestigating reflection and refraction of light
Global Challenges
Stopping distance, acceleration and collision force calculations
- 2 things to know
- Paper 12 (Physics)
Overview
Adding thinking and braking distance to find a stopping distance, estimating thinking distance from speed and reaction time, estimating the accelerations and decelerations of cars, the resultant forces on an accelerating car and motorcycle and on a car in a crash, and why collision forces are so much larger than in ordinary driving.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Process
Why are the forces in a collision so much larger than the forces in ordinary driving?
Questions from this subtopic
Each one with the model answer underneath.
- 1
A driver has a thinking distance of 15 m and a braking distance of 38 m. What is the overall stopping distance?
Model answer
53 m.
- 2
A driver's reaction time is 0.7 s and the car is travelling at 20 m/s. Estimate the thinking distance.
Model answer
14 m, found by multiplying the speed by the reaction time.
- 3
A car speeds up from rest to 24 m/s in 6 s. Estimate its acceleration.
Model answer
4 m/s².
- 4
Estimate the resultant force on a 1000 kg car that is accelerating at 4 m/s².
Model answer
4000 N.
- 5
A car travelling at 15 m/s is brought to rest in 0.1 s in a crash. Estimate the deceleration.
Model answer
150 m/s².
- 6
Estimate the force on a 1000 kg car that decelerates at 150 m/s² in a collision.
Model answer
150000 N.
Other ways to work this
The same content, four other ways.
What is inside Levo
Six ways to work the same material.
Every question in Global Challenges, on a schedule.
Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.
Or £46 a year, about £3.83 a month. Cancel anytime.