A quiet pedestrian crossing on a red-brick terraced UK town street in soft morning light, with an older person walking across the road carrying a cloth shopping bag
AI-generated image, not a photograph of a real person or place.
velocityspecs

SPEED, IN PLAIN NUMBERS

How fast is
everyday life?

METRES per second

  • Speed has no direction
  • Velocity does
  • Typical, not exact
  • A few numbers, a clearer picture

Speed is how far, how fast. Velocity adds which way.

GCSE physics gives a few typical values worth knowing: about 1.5 m/s walking, 3 m/s running and 6 m/s cycling. Put them next to road limits and the speed of sound and the numbers start to make sense.

Updated

Compare speeds

THE SHORT ANSWER

Same speed,
different velocity.

Speed is a number.
Velocity is a number with a direction.

SPEED

How far each second

Speed is distance travelled per unit of time. The AQA physics specification takes walking as about 1.5 m/s, running 3 m/s and cycling 6 m/s.

Compare speeds

VELOCITY

Speed with a direction

Velocity is speed in a given direction. Something going round in a circle can keep a constant speed while its velocity changes.

Why it matters

CROSSINGS

Built around 1.2 m/s

UK pedestrian crossings assume a walking speed of at least 1.2 m/s. A study found most people over 65 walk more slowly than that.

See the numbers

A QUICK SPEED CHECK

How fast
is it going?

Pick something that moves to see its typical speed in metres per second. The bar shows roughly where it sits, from a stroll to the speed of sound.

Speed check

Choose something moving
Walking≈ 1.5 m/s

A typical walking pace in the AQA specification. Age, terrain and fitness all change it.

Running≈ 3 m/s

About twice a typical walking pace, as a typical value for GCSE physics.

Cycling≈ 6 m/s

A typical cycling speed, about four times walking pace.

A car at 30 mph≈ 13 m/s

30 mph (48 km/h) is the national limit on roads with street lights in England, Scotland and Northern Ireland; Wales uses 20 mph.

Sound in air≈ 330 m/s

A typical value for sound in air. Like wind, the speed of sound varies with conditions.

Sources: AQA GCSE Physics (8463) specification, section 4.5.6.1; GOV.UK Speed limits.

Typical values from the AQA GCSE Physics specification; road figures are UK limits converted by us (1 mph is about 0.447 m/s). Real speeds vary with age, terrain, fitness and conditions.

TWO NUMBERS WORTH KNOWING

The green man
assumes a pace.

One figure crossings are designed around,
one on how many older people fall short of it.

1.2 m/s

Walking speed assumed by UK crossings

Researchers compared this assumption with timed walks by 3,145 adults aged 65 and over in the Health Survey for England 2005. Average speeds were 0.9 m/s for men and 0.8 m/s for women.

CROSSING TIMES · AGE AND AGEING 2012

84%

Men over 65 slower than 1.2 m/s or unable to do the test

For women aged 65 and over the figure was 93%. The authors concluded that 1.2 m/s is inappropriate for older adults and that crossing timings should be reconsidered.

OLDER PEDESTRIANS · AGE AND AGEING 2012

Walking impairment in the study meant a speed below 1.2 m/s over an 8-foot walk at normal pace, or not taking the test because it was unsafe or not possible.

FOUR WAYS TO USE IT

Make speeds
make sense.

An empty playground roundabout spinning in a park, its painted rails blurred into a circle of motion
AI-generated image, not a photograph of a real person or place.

You do not need a speedometer. A tape measure, a timer and the equation distance = speed × time go a long way.

  1. Time a known distance

    Walk a measured 10 metres and time it. Divide distance by time to get your speed in m/s.

  2. Compare with 1.5 m/s

    Set your result against the typical walking value. Remember that speed varies with age, terrain and fitness.

  3. Add a direction

    Say which way as well as how fast, and you have a velocity: 1.5 m/s north is not the same as 1.5 m/s south.

  4. Convert road limits

    Multiply mph by about 0.447 for m/s. A 30 mph car covers roughly 13 metres every second.

THE ULTIMATE SPEED

Light sets
the metre.

A cyclist seen from behind riding along a tree-lined country lane, the hedges slightly blurred with movement
AI-generated image, not a photograph of a real person or place.

The speed of light in a vacuum is exactly 299 792 458 m/s. It is exact because the metre itself is now defined from it, alongside the second.

According to the BIPM, one metre is the distance light travels in a vacuum in 1/299 792 458 of a second. Every speed on this page, from a stroll to sound, is measured against that fixed number.

Questions

Questions people ask

What is the difference between speed and velocity?

Speed is how fast something moves and has no direction, so it is a scalar. Velocity is speed in a given direction, so it is a vector.

Can speed stay the same while velocity changes?

Yes. An object moving in a circle at a steady speed is always changing direction, so its velocity changes even though its speed does not.

How fast does a person walk?

The AQA GCSE Physics specification takes about 1.5 m/s as a typical walking speed, while noting that speed depends on age, terrain, fitness and distance.

What walking speed do pedestrian crossings assume?

A 2012 study in Age and Ageing described UK crossings as needing a walking speed of at least 1.2 m/s, and found most people over 65 walked more slowly than that.

Why is the speed of light an exact number?

Since the metre is defined by fixing the speed of light at 299 792 458 m/s, that value is exact by definition, according to the BIPM.

Sources

Where the facts come from

  1. AQA GCSE Physics 8463 specification: Forces (speed and velocity)
  2. Asher et al. (2012) Most older pedestrians are unable to cross the road in time, Age and Ageing (Europe PMC)
  3. GOV.UK: Speed limits
  4. BIPM: SI base unit, the metre

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