Many students think that a compact object (such as a ball or a stone) falls at a constant speed which depends on how heavy it is
Misconception
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.
In Q4, the wording states that ‘forces caused by the air’ can be ignored. If so, the balls should land exactly together – a result which some pupils may recall as the ‘right answer’. For that reason, part (b) provides a useful check on understanding.
EPSE Gravity Q4Q5 is similar to Q4, but has the advantage of being less wordy. For objects of mass 1kg and 2kg, the correct answer is A, though B might also be defended as plausible.
EPSE Gravity Q5The situation in Q6 is significantly different from that in Q5, as here the weight/area ratio for the table tennis ball is very much smaller than for the golf ball.
EPSE Gravity Q6Resources to Address This
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Estimate of acceleration due to gravity using pulsed water drops (11-16)
Source - Practical physics/ Force and motion/ acceleration due to gravity
This experiment is one of the most delightful demonstrations in physics and well worth the effort of assembling the equipment.
View Resource
References
The following studies have documented this misconception:
- Gunstone, R. F. and White, R. T. () Understanding of Gravity. Science Education, 65 (3),
291-299.
This study presented a sample of first year physics undergraduates at Monash University, Australia, with eight physical situations. The students were asked to make predictions as to what would happen if a certain action was taken. The action was then taken, and the subjects were asked to explain any discrepancies between their prediction and the result.
Review sheet - Halloun, I. A. and Hestenes, D. () Common sense concepts about motion. American Journal of Physics, 53 (11),
1056-1065.
This study surveyed and analysed the common sense beliefs on motion of a sample of 478 university physics students at Arizona State University using a multiple choice diagnostic test on the subject of mechanics. 22 students were randomly chosen for follow-up interviews. A taxonomy of common sense concepts which conflict with Newtonian theory was developed as a guide for instruction.
Review sheet - Dilber, R.; Karaman, I. and Duzgun, B. () High school students' understanding of projectile motion concepts. Educational Research and Evaluation, 15 (3),
203-222.
This study analysed a sample of 82 high school students (36 boys and 46 girls) between the ages of 16 and 17 using a qualitative multiple choice test on projectile motion. The test was administered both prior to and after a 4-week instructional period. The study took place in the department of physics at Ataturk University, Erzurum, Turkey.
Review sheet