What does displacement measure?

The straight-line distance from the starting point to the finishing point, together with its direction.

Which of speed and velocity is the vector, and what extra information does it carry?

Velocity is the vector, and it carries the direction of travel as well as the size of the speed.

A runner completes exactly one lap of a 400 m track. What distance has she covered and what is her displacement?

The distance is 400 m and the displacement is zero, because she finishes where she started.

A student walks 30 m east and then 40 m north. What distance has she walked and what is the size of her displacement?

She has walked 70 m, and her displacement is 50 m, because the two legs form a right-angled triangle with a hypotenuse of 50 m.

OCR GCSE Combined Science Physics J250

Electricity

Topic overview Charge, and producing static electricity Transfer of electrons in charging and discharging Current as a rate of flow of charge Charge, current and time Series and parallel circuits, and circuit symbols Current, potential difference and resistance Resistors whose resistance changes, and investigating them Linear and non-linear circuit elements from graphs Net resistance in series and parallel Circuits for measurement, and electrical power

Energy

Topic overview Conservation of energy, and energy stores Energy changes on heating, and calculating them Energy of a moving body, a spring and a raised object Dissipation, and energy transfer in domestic devices Power ratings, and calculating efficiency Reducing unwanted energy transfer, and the rate of cooling

Forces

Topic overview Measuring distance and time, and calculating speed Converting units, and rates Vectors and scalars in motion Distance-time and velocity-time graphs Average speed, and the equations of uniform motion How objects interact, and forces as vectors Newton's first law Newton's second law Work done, and stored energy Power, and Newton's third law Stretching, bending and compressing; elastic and plastic Force and extension, linear and non-linear The spring constant, and work done in stretching Gravitational fields, weight and free fall Calculations with weight and gravitational field strength

Global Challenges

Topic overview Typical speeds and everyday accelerations Reaction time, stopping distance and the dangers of large decelerations Stopping distance, acceleration and collision force calculations Energy resources, and trends in their use The national grid, and step-up and step-down transformers Why the national grid is efficient, and power in a transformer Mains electricity: a.c., d.c. and the domestic supply Live, neutral and earth wires, and electrical danger

Magnetism and Magnetic Fields

Topic overview Permanent and induced magnets, and magnetic poles Magnetic fields, and the dipping compass The magnetic effect of a current, and solenoids

Matter

Topic overview How the atomic model changed, and the structure of the atom The size of atoms, and defining density Density of the states of matter, and density calculations Conservation of mass in changes of state Heating a system, and specific heat capacity Calculations with specific heat capacity and latent heat Gas molecules, temperature and pressure

Radioactivity

Topic overview Protons, neutrons and isotopes Unstable nuclei and the emissions they give out Balancing nuclear equations Electron energy levels, and radiation from atoms Half-life and the randomness of decay Penetration of alpha, beta and gamma Contamination and irradiation, and reducing the hazard

Waves in Matter

Topic overview Amplitude, wavelength, frequency and period The wave equation Transverse and longitudinal waves Modelling waves with ripples and sound Electromagnetic waves as transverse, and energy transfer Frequency and wavelength across the spectrum What our eyes detect, and light as an electromagnetic wave Uses of electromagnetic waves Hazards of ultraviolet, X-rays and gamma rays Investigating reflection and refraction of light

Forces

Vectors and scalars in motion

3 things to know
Paper 5 (Physics)

Overview

The difference between a scalar and a vector, why distance is a scalar and displacement a vector, how velocity differs from speed, and journeys where the two disagree.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Explain the difference between a scalar and a vector, and how displacement and velocity differ from distance and speed.

Key term

What is the difference between a scalar quantity and a vector quantity?

Key term

Is distance a scalar or a vector, and why?

Questions from this subtopic

Each one with the model answer underneath.

1
What is the difference between a scalar quantity and a vector quantity?
Model answer
A scalar has size only, while a vector has both a size and a direction.
2
Is distance a scalar or a vector, and why?
Model answer
A scalar, because it is only the total length of the path travelled and carries no direction.
3
What does displacement measure?
Model answer
The straight-line distance from the starting point to the finishing point, together with its direction.
4
Which of speed and velocity is the vector, and what extra information does it carry?
Model answer
Velocity is the vector, and it carries the direction of travel as well as the size of the speed.
5
A runner completes exactly one lap of a 400 m track. What distance has she covered and what is her displacement?
Model answer
The distance is 400 m and the displacement is zero, because she finishes where she started.
6
A student walks 30 m east and then 40 m north. What distance has she walked and what is the size of her displacement?
Model answer
She has walked 70 m, and her displacement is 50 m, because the two legs form a right-angled triangle with a hypotenuse of 50 m.

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