Many students do not clearly distinguish the ideas of instantaneous and average speed
Misconception
Resources to Address This
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Speed limits (11 - 14)
This resource supports classroom discussions on how average speed differs from instantaneous speed.
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Average speed and instantaneous speed (11 - 14)
It is common to use the term speed rather than average speed. Many teachers drop the term average thinking it may add an additional level of difficulty. We would nevertheless recommend that you encourage your pupils to make the distinction between instantaneous speeds and average speeds wherever possible. One way to do this is to restrict the use of average speed to refer to a whole journey.
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Instantaneous and average velocities (11 -16)
You can use a sensor data logging system to experience the difference between instantaneous and average velocity.
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Episode 205: describing motion (16 - 18)
This is an area which many students find difficult and they may well remember their pre-16 experience with some unease. It is worthwhile including a direct measurement activity to ensure that students spend sufficient time on the basic physics of velocity, distance and time.
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References
- Trowbridge, D. E. and McDermott, L. C. () Investigation of Student Understanding of the Concept of Acceleration in One Dimension. American Journal of Physics, 49 (3), 242-253.
US-based researchers investigated 19-year-olds ability to apply the concept of acceleration when interpreting the motions of real objects. They found that students struggled to grasp acceleration in the time usually allotted, suggesting the need to dedicate more time to basic kinematic concepts at the introductory level, even at the cost of advanced topics.
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