Speed: Typical values may be taken as:

The idea

This statement introduces the typical speed values that support the earlier idea that walking, running and cycling speeds vary. In GCSE Combined Science you should recall approximate values and use them to judge whether a calculated answer is reasonable. A person walking typically moves at about 1.5 m/s, running at about 3 m/s, and cycling at about 6 m/s, though these are guides rather than exact constants. For example, a 1500 m walk at 1.5 m/s takes about 1000 s, while the same distance run at 3 m/s takes about 500 s. Use typical values to estimate times, check units and identify unrealistic answers, such as a walking speed of 30 m/s. Always state that actual values depend on age, terrain, fitness and distance travelled.

What earns the marks

• Recall approximate typical speeds: walking about 1.5 m/s, running about 3 m/s, and cycling about 6 m/s.
• Use a typical value with speed = distance ÷ time to estimate a time or distance, for example time = distance ÷ speed.
• Check whether a calculated speed is reasonable by comparing it with the typical range for that activity.
• Convert between m/s and km/h where needed, remembering that 1 m/s = 3.6 km/h.
• Explain that typical values are approximate because age, terrain, fitness and distance travelled change actual speed.
• Select the most appropriate typical value when comparing modes of transport, such as walking versus cycling over the same distance.

Common mistakes and how to put them right

• Treating typical values as exact constants.

  Put it right by saying they are approximate guides that vary between people and conditions.

• Using the wrong unit.

  Put it right by giving walking, running and cycling speeds in m/s and converting if a question asks for km/h.

• Dividing time by distance instead of distance by time.

  Put it right by rearranging speed = distance ÷ time to time = distance ÷ speed.

• Accepting an unreasonable answer.

  Put it right by comparing the result with typical values, for example rejecting a running speed of 50 m/s.

Exam tips

• Learn the approximate values walking ≈ 1.5 m/s, running ≈ 3 m/s and cycling ≈ 6 m/s, and quote them when estimating.
• Show the rearrangement you use, such as time = distance ÷ speed, before substituting numbers.
• Use typical values to sanity-check answers and comment briefly on whether the result is realistic.
• Keep units consistent throughout a calculation and convert km/h to m/s by dividing by 3.6 when necessary.