I know that the dimples on golf balls allow them to fly further. But before dimples, protruding nodules were used. What is the difference between the two? Why are dimples better than nodules?

Billy Vine, Cardiff, UK

Being the heaviest organism on the planet (ignoring anything that photosynthesises or any ridiculously big fungi), baring in mind it lives in water, a blue whale is a huge lump of a mammal and probably has the capacity to reach some speed if given a chance and could probably cause great distress to krill populations if it where to waste more energy painting on go faster stripes. What's the fastest a blue whale has ever been recorded? It has probably never felt the need to outrun a predator or to leap on unsuspecting krill, and isn't really built for speed and has never seen the point in chasing after...anything at all...except krill...and maybe to out compete males if it itself is a male. Theoretically how fast could a blue whale swim if it let it's metaphorical hair down?

Being the heaviest living organism on the planet (that doesn't photosynthesise or isn't a ridiculously big fungi) , baring in mind that it lives in water, what's the fastest a Blue whale has been recorded swimming? being a huge lump of a mammal, it has probably never felt the need to out run anything or take on random spurts of speed to leap on krill, nor is it built to race...much at all...except krill..and maybe other blue whales for a mate. but theoretically how fast could a Blue Whale be if it let it's metaphorical hair down? Thomas Frost, Suffolk, UK

I contend that the fastest human powered object would be the smallest thing that could be engineered by humans  fired by a linear accelerator powered by chris hoy on a bike but how fast could that theoretically go? And what could be faster?

If a space craft uses a laser to push it along in space could it at one point hit the speed of light?

How fast would a formula one car need to go to drive upside down for a period of time and could it actually be done?

I just re-watched a show called 'megstructures' where they featured a rollercoster called kingda ka that reached over 200kph in 3.5 seconds and is also the tallest in the world. 

If we put cost aside, and only focus on a) human ability to withstand ride and b) the ability of the physical structure to withstand.  could we potentially see roller costers the height of buildings going at yet unseen speeds and heights?

i understand how some trained people can withstand g forces like fighter pilots.  But keep in mind rides need to be for general public.

On a long haul flight I wondered with the amount of people who now fly, and the amount of money airlines make, surely one that was as big as an Airbus yet as fast as a concorde would certainly dominate the market in which people want to use.

I am not only concerned with cost as I am sure they would make the money back, but is it possible to make such a big plane fly so fast? 

I heard that a Formula 1 car travelling at 200 kilometres per hour would generate enough downforce (or suction) to allow it to stick to the ceiling.

Is this correct? And if it is, how is the force generated?

Robert Webber, Melbourne, Australia

(Image: mzacha, stock.xchng)

This is an interesting thought-experiment and gave us some great answers. Clearly the long-running debate over how aircraft wings achieve lift is still alive and kicking - Ed