# Many students think a heavy or fast-moving object has more force than a light or slow-moving one

Forces and Motion

Misconception

Furthermore, students may think that evidence for this is provided by the difference between high-speed and low-speed collisions, or between collisions of heavy objects versus collisions of light objects.

• Adding mass to a moving system (11-16)

Drop an extra load onto a moving trolley

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• Episode 221: Elastic collisions (16-19)

This episode extends the idea of conservation of momentum to elastic collisions, in which, because KE is conserved, useful information can also be found by calculating the changes in KE of the colliding objects.

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## References

• Bliss, J., Ogborn, J. and Whitelock, D. () Secondary school pupils' commonsense theories of motion. International Journal of Science Education, 11 (3), 263-272.

Asking students to analyse images from comic strips, rather than the more common force diagrams used in lessons, can be useful in establishing students' understanding of forces. The approach also helps to identify misconceptions, based on students ‘common sense’ when they give their descriptions. These ideas are often resilient to change and need to be explicitly challenged in teaching and learning activities.

Paper digest

• Twigger, D., Byard, M., Driver, R., Draper, S., Hartley, R., Hennessy, S., Mohamed, R., O'Mally, C., O'Shea, T. and Scanlon, E. () The conception of force and motion of students aged between 10 and 15 years: an interview study designed to guide instruction. International Journal of Science Education, 16 (2), 215-229.

Students can be very unclear about the difference between energy and force, often believing that they are the same thing. This leads then to the idea that objects slow down because they are ‘using up’ energy, rather than realising that forces are acting to change the motion. This study suggests that careful analysis of motion graphs, coupled with force diagrams can help overcome these issues and that the concept of momentum should be introduced earlier in many courses.

Paper digest

• Maloney, D. P. () Rule-governed physics: Some novice predictions. International Journal of Science Education, 7 (3), 295-306.
• Graham, T. and Berry, J. () Students' intuitive understanding of gravity. International Journal of Mathematical Education in Science and Technology, 24 (3), 473-478.

This study administered a questionnaire to a sample of 202 students in the UK between the ages of 16 and 18 from a range of city and rural comprehensive schools, private schools and sixth-form colleges.

• Watts, D. M. () A study of schoolchildren's alternative frameworks of the concept of force. International Journal of Science Education, 5 (2), 217-230.

This study used an interview approach to identify the conceptions of force of 12 students aged 11-17. Students were drawn from a range of schools in the Greater London area, from both junior science classes and advanced-level physics classes.

• Brown, D. E. () Students' Concept of Force: The Importance of Understanding Newton's Third Law. Physics Education 24 (6) 353-357.

• Osborne, R. () "Building on Children's Intuitive Ideas" in R. Osborne & P. Freyberg (Eds.), Learning in Science. Heinemann, Auckland, 41-51.