Measuring speed accurately
I can clearly describe how to measure speed and explain how I can do this accurately.
- Year 8
Measuring speed accurately
I can clearly describe how to measure speed and explain how I can do this accurately.
Lesson details
Key learning points
- The instantaneous speed of an object is the speed at a particular moment in time.
- For an accurate measurement a person needs to be in line with the observation.
- Manual timing can lead to a range of timing errors.
- Repeat readings can reduce the effect of random errors.
- Some readings are anomalous and these should not be used in caluations of averages.
Keywords
Average speed - The average speed of an object is the distance it travels per unit of time, measured in metres per second (m/s). It is a scalar quantity.
Instantaneous speed - The instantaneous speed of an object is its speed at a particular moment.
Timing error - Manual timings include some timing errors. These can be due to reaction times or observing from incorrect positions.
Random error - Random errors are errors that vary from test to test in an uncontrolled way.
Common misconception
Pupils commonly confuse instantaneous and average speeds.
Be very careful when using the word speed, always use 'average' or 'instantaneous' explicitly, linking average speed to a time period.
Equipment
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.Match the units to the quantities they are used to measure.
Q2.Which of these equations shows how distance travelled can be calculated from average speed and time?
Q3.Starting with the slowest, sort these objects in order of speed.
Q4.A student measures how long a trolley takes to fall a distance of 1.5 m three separate times. Their readings are 2.5 s , 2.1 s, and 2.0 s. Calculate the average roll time.
Q5.A trolley was allowed to roll along a series of tracks of different steepness giving different average speeds. Starting with the slowest, sort the results in order of increasing average speed.
Q6.A toy car rolls through a distance of 3.2 m in a time of 1.6 s. Calculate the average speed of the trolley giving the correct unit.
Assessment exit quiz
6 Questions
Q1.Match the key words to the explanations.
