Do You Think You're Clever? Read Free

were good,

The world would be nicer than ever

We thought that it possibly could.

But somehow it’s seldom or never

The two get along as they should.

The good are so harsh to the clever,

The clever so rude to the good.

What happens when I drop an ant?
    (Physics, Oxford)
    You could answer this question in all kinds of ways – the humorous and human, the absurdly trivial or the grandly existential. But this was a physics question, so it makes sense here to address the science of formicine precipitation.
    The first answer, then, might be to say that the ant, which if it’s the wingless kind can’t fly, falls to the ground – accelerating earthwards as it’s pulled down by the mutual gravitational attraction between the ant and the earth. Splat. But there is more to it than that. Ants are so small and light that their fall is considerably slowed on the way down by air resistance – by the collision of the ant with countless air molecules. So while a human skydiver can reach a maximum, or ‘terminal’, velocity of, say, 50–90 m/s, most ants are so light that their terminal velocity is slow enough for them to drift earthwards gently and for them to survive both the speed of the fall and the impact with the ground.
    In fact, recent research in tropical Peru has shown that wingless worker ants are among the world’s flying, or rather gliding, animals. When an ant is dropped, it first tumbles vertically. But like a skydiver in the first stages of freefall, it splays its legs to increase drag and gain control. Eventually, by moving its legs to control direction through drag, it eases into a gentle glide at about 4 m/s. It apparently glides backwards because its hindlegs are longer than its forelegs.
    The physics doesn’t stop here, though, because even in a simple action like dropping an ant, there is a complex assemblage of forces, reactions and consequences. We must remember, for instance, that gravity is a mutual force. So when you drop an ant it might fall towards the ground, but at the same time the earth is moving upwards to meet the ant. Of course, the mass of the ant is so small and the mass of the earth so great that the movement of the earth is immeasurably small, but we can be sure from other fine measurements that it really does happen. Moreover, as Newton’s Third Law of Motion makes clear, there is an equal opposite reaction to every action. So the act of dropping the ant will have its own, undetectably small, kick-back on your hand.
    And as we talk about undetectably small movements, we are reminded of chaos theory and Edward Lorenz’s famous suggestion that ‘the flap of a butterfly’s wings in Brazil sets off a tornado in Texas’ – as the tiny movement of the air caused by the butterfly’s wings sets in train an escalating, multiplying whirl of movements in the air that culminates in a tornado far away. So, even such a small-scale event as dropping an ant could have manifold unpredictable consequences on every scale from the minuscule to the gigantic. So, actually, it’s impossible to say, on a certain level, what happens when you drop an ant.
    Einstein’s General Theory of Relativity adds another aspect to this seemingly trivial event. Einstein explained gravity as working through the distortion of the fabric ofspacetime. So even a small movement of mass – the mass of the ant towards the earth – will minutely alter the fabric of spacetime. And of course the movement of the ant and the movement of the earth will, as Einstein’s Special Theory of Relativity shows, cause an (unimaginably small) shift in the time relation between you and the ant …
    Ultimately, it all depends on what you want to know.

Why is the pole vaulting world record about 6.5 metres and why can’t it be broken?
    (Computer Science, Cambridge)
    Even a kangaroo can’t get very high from a standing jump. That’s why both conventional high-jumpers and pole-vaulters use a run-up. Instead of accelerating against