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Question 5Two balls of different weight (B is heavier than A) are dropped at the same moment but from different heights (see figure).
(a) The lower ball hits the ground first.
(b) The higher ball hits the ground first.
(c) Both balls hit the ground at the same time, if the difference in distance of fall corresponds to the difference in weight. The reason for answer c was to test, if the knowledge of our students is stable and that they know, that for dropping object, mass can be neglected. Without this answer c, I believe that most students would have answered correctly. But more than half of our students do not have a stable knowledge about a fact, which they have been told many times by their physics teachers. 5.2 Which ball is going faster when it hits the floor?
c) both balls are going the same speed when they hit the floor. This result seems to be ok. But in the light of item 5.1 it can be asked, how many students think: the heavier, the faster and not: the higher the faster? |
5.1. Which of the following statements is correct?
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