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Many students find it difficult to apply certain physics concepts to their daily lives. This is especially true when they perceive a principle taught in physics class as being in conflict with their experience. An important instance of this occurs when students are instructed to ignore the effect of air resistance when solving kinematics problems. To a student, this assumption disconnects from their everyday experience. Mathematically, ignoring the effect of air resistance is crucial, however, since it renders such problems tractable. However, this step is rarely, if ever, provided with justification in undergraduate texts, leading students to believe that what they are taught does not apply to their everyday experience. Taking the additional step of clarifying when it is reasonable to ignore air resistance makes students' reconciliation of their everyday experiences with the physics principle of free fall more likely. In this paper we develop a graphical tool intended to make this step as simple and effective as possible. We do this by summarising the results of a set of numerical simulations of various balls falling under the effects of both gravity and air resistance by means of a carefully chosen graph: a plot of an object's cross-sectional surface are versus its mass. We further use our numerical results to evaluate how these two variables relate to the effects of air resistance for balls dropped from varying heights.

Introduction Prenatal androgen exposure has important organizing effects on brain development and therefore on future behavior. Previous research has shown, that the ratio between index finger (2D) and ring finger (4D) (2D:4D) could function as a marker of prenatal androgen effects, with a relatively shorter 2D indicating a higher prenatal androgen exposure. 2D:4D is associated with status-seeking and competitive behavior but also with altruism. Therefore, 2D:4D should be related to academic success. Methods We examined the 2D:4D of both hands, as well as the difference between both variables (Dr-l), of 209 university graduates (74 women) employed at the Medical Faculty of the Friedrich-Alexander-University Erlangen-Nürnberg, Germany, and we assessed the relationship of these variables with academic career performance. Career performance was measured by the number of publications as first or last author, and by achievement of an academic degree used in many European countries, the so-called “Habilitation”. Results In a within-sex analysis we found a non-monotonic association between the right hand digit ratio and the probability of having a “Habilitation” in females. Academic success, measured by the number of publications as first or last author and the probability of a "Habilitation", increases with age. In agreement with the literature, we found higher academic success in men. Conclusion We found a non-monotonic relationship between right hand 2D:4D and academic success in females. However, the significance of this relationship was weak.

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