Category Archives: Opinion

Teardrop cars

Car manufacturers spend millions on streamlining cars for lower air resistence. But what is the most efficient shape for a car to be?

Look at water droplets travelling through air. As a liquid, surface tension keeps the molecules together as a drop. In a vacuum, water drops are spherical as surface tension forces minimise the surface area. Travelling through air, water takes on the characteristic tear-drop shape – air resistance flattens the front while forming a streamlined “tail” at the rear.

Liquids will take the shape created by the combination of the forces acting on it (eg. the edges and base of a glass combined with gravity). Thus a teardrop shape is probably the most efficient shape for an object to take while travelling through air. Similarly this should hold for submarines travelling through water.

Indeed dolphins and whales seem to be shaped a little like this as well – a large bulbous head tapering to a thinner tail.

Perhaps in the future, as fuel becomes more scarce and thus air resistance issues become more important for greater fuel efficiency, cars may look more like this as well.

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Filed under Observation, Opinion, Science

Lights, sounds and infants

Ventriloquism works when people trust their eyes rather than their ears (see Ventriloquism entry). But this isn’t true for humans of all ages.

In the womb, babies can hear but not see. Thus when born, infants show a marked preference for sounds rather than images. This appears to extend at least until a child is 4 or 5 years old. It has been suggested that it may be this preference which could drive the child to try to understand the language spoken around it – and thus learn to speak.

To my knowledge, no-one has tested for ventriloquism  effects in infants – but my guess is that they would show a reverse ventriloquist effect.

References

Robinson, C.W. and Sloutsky, V.M. (2004) Auditory Dominance and Its Change in the Course of Development. Child Development 75 (5), 1387-1401.

Sloutsky, V. M, & Napolitano, A.C. (2003). Is a picture worth a thousand words? Preference for auditory modality in young children. Child Development, 74 (3), 822-833.

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Filed under Opinion, Science