Many students conflate velocity with speed
Misconception
Students may also believe that instantaneous and average speeds and velocities are always the same size.
Diagnostic Resources
The following worksheets may help to identify whether students hold this particular misconception.
For more information, see the University of York EPSE website.
This question involves a graphical depiction of motion with a change of direction, so a velocity-time graph is used. The key idea is that the slope of a distance-time graph is an indication of speed (or velocity), but that the sign is indicative of the direction of that motion.
EPSE Motion Q36This question probes the ability to interpret velocity-time graphs in terms of the direction of motion as well as the magnitude (i.e. speed).
EPSE Motion Q37Resources to Address This
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What about velocity? (11-14)
This resource gives an accessible explanation of the difference between velocity and speed.
View Resource
References
- Jones, A. T. () Investigation of Students' Understanding of Speed, Velocity and Acceleration. Research in Science Education, 13 (1), 95-104.
From this study, it is clear that students can conflate velocity, speed and acceleration. With a sample of 30 students aged 11-16 in the US, the researchers found that confusion around one object passing another appeared regularly.
Paper digest - Champagne, A. B.; Gunstone, R. F. and Klopfer, L. E. () "Effecting changes in cognitive structures among physics students" in West, L. H. T. and Pines, A. L. (eds), Cognitive Structure and Conceptual Change. Academic Press, Pittsburgh, 163-187.
This study aimed to probe the cognitive structure of 13 'academically gifted' middle school students in the US, as well as six non-physics major university science graduates studying to become high school science teachers. Five tests of cognitive structure were used on either side of a 10-week instructional period.