New
New
Year 10
AQA
Foundation

Measuring the speed of water waves from distance and time

I can explain how to make measurements of distance and time to accurately measure the speed of water waves.

New
New
Year 10
AQA
Foundation

Measuring the speed of water waves from distance and time

I can explain how to make measurements of distance and time to accurately measure the speed of water waves.

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Lesson details

Key learning points

  1. The speed of water waves can be measured using measurements of distance travelled and time taken.
  2. Random errors are made when the method limits how accurate a measurement can be.
  3. The effect of random errors can be reduced by repeating readings and calculating a mean.
  4. The uncertainty in a mean result is calculated from half the range of the repeat measurements.

Common misconception

Calculating a mean of repeat readings reduces (random) errors in measurements.

Calculating a mean reduces the effect that random errors have on a final result. The random errors in the original readings are unaffected.

Keywords

  • Random error - A random error is caused by unpredictable factors that affect the measurement of a variable.

  • Uncertainty - Uncertainty is an estimate of how far from the true value a measurement might be. It is equal to half the range of repeat measurements.

  • Mean - The mean is calculated by adding each measurement and dividing by the number of measurements.

  • Anomalous result - An anomalous result is a measurement that is a mistake. A line should be drawn through it and it should not be used to calculate a mean.

In class, demonstrate the practical using the actual equipment the students will use rather than watching the video of example data being collected. The practical task should be quite quick and should reinforce the focus on measuring techniques.
Teacher tip

Content guidance

  • Equipment requiring safe usage.

Supervision

Adult supervision recommended.

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Video

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6 Questions

Q1.
Match the following quantities to their units.
Correct Answer:distance,metres (m)

metres (m)

Correct Answer:time,seconds (s)

seconds (s)

Correct Answer:speed,metres per second (m/s)

metres per second (m/s)

Q2.
Which of the following is the correct equation for speed?
speed = distance x time
speed = distance + time
speed = distance – time
Correct answer: speed = distance ÷ time
Q3.
Which of the following is not a unit of speed?
metres per second (m/s)
Correct answer: metres per second squared (m/s²)
kilometres per second (km/s)
miles per hour (mph)
Q4.
Sam take three repeat measurements for the time taken for a wave to travel a set distance. The results are 0.21 s, 0.19 s and 0.26 s. Calculate the mean time. You do not need to include the units.
Correct Answer: 0.22, 0.22 s, 0.22 seconds, 0.22s, 0.22seconds
Q5.
What effect do random errors have on repeat readings?
Random errors make repeat readings identical.
Correct answer: Random errors make repeat readings slightly different to each other.
Random errors make repeat readings more accurate.
Random errors make all repeat readings inaccurate by the same amount.
Q6.
The uncertainty in a measured value refers to ...
the accuracy of the result.
the validity of the result.
Correct answer: the amount of doubt about the result.
the amount of certainty about the result

6 Questions

Q1.
Which of the following are SI (International System of Units) units of distance and time?
Correct answer: metre
Correct answer: second
mile
hour
Q2.
Which of the following is the SI unit of speed?
Correct answer: metres per second
kilometres per hour
miles per hour
Q3.
Which of the following affects the speed of a water wave?
Correct answer: the type of water (i.e. how much salt it contains)
the shape of the water wave
the number of waves per second
Q4.
Why are repeat measurements taken when measuring the time it takes a water wave to travel a set distance?
Correct answer: errors can be identified and discounted or repeated
reaction times improve with practice
mistakes are often made with the first measurement
Q5.
What is the name given to the type of error caused by differences in a person’s reaction time?
predictable
Correct answer: random
systematic
human
Q6.
A result that is close to the true or expected value is .
Correct Answer: accurate

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