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gravity from zero, the jumper uses the momentum of the run-up to boost upward acceleration. The vaulter’s pole enables the maximum possible momentum to be converted into upward acceleration. In terms of physics, it uses the leverage of the pole to convert the kinetic energy of the sprint run-up to combat gravity, or more specifically gravitational potential energy. And it’s in the physics that the limits to the heights that can be achieved by a pole-vaulter lie.
    Ideally, a vaulter would convert all the kinetic energy of his sprint into vertical acceleration to combat gravity. Of course, in practice, even if he achieves the perfect lift-offsome energy will be lost to friction and in things such as the bending of the pole. So pole construction and design is important. Nonetheless, it is possible to calculate the maximum height a vaulter could reach in the ideal circumstances. The limit ultimately depends on the run-up speed.
    You can calculate the maximum kinetic energy the vaulter has available from his mass (that is, his body weight) and his velocity, using the formula: half mass times the velocity squared, or KE = ½mv 2 . You can calculate, too, the gravitational potential energy that it has to be converted into using the formula: the acceleration due to gravity times the vaulter’s mass times the height, or PE = gmh, where g = 9.8 m/s 2 . The vaulter’s mass appears on both sides of the equation, and so cancels out. And so you can say the maximum height the vaulter can reach is half of the square of his velocity when divided by the acceleration due to gravity, h = (½v 2 /g). You’d have to make small adjustments according to the vaulter’s own height and centre of mass, but this way you can get a very rough figure of the height the vaulter could potentially reach.
    Experts suggest the best that vaulters will ever achieve is about 6.4 metres, because of the limits to their run-up speed. The world record currently stands at 6.14 metres, set by Ukrainian Sergey Bubka on 31 July 1994. Altogether, just seventeen men have ever exceeded 6 metres in a vault. Women, who are generally shorter and able to reach slower run-up speeds, can vault less high. Just one woman, Yelena Isinbayeva, has ever exceeded 5 metres, and experts think the highest that women vaulters are likely to reach is about 5.3 metres.

If you could go back in time to any period of history, when would it be and why?
    (Law, Oxford)
    Who would not jump at the chance to go back even to yesterday, to live moments of your own life again, and see if with hindsight things could and would have been different? And who could resist the astounding opportunities offered by a Tardis voyage into deeper history? To step into, or even to catch a fleeting glimpse of the real, living, breathing, happening long-lost world of the past would be such a glorious, heart-stopping piece of magic that you’d take whatever was offered without worrying about choice. How amazing it would be to watch the dramatic highlights of history as an eyewitness – Julius Caesar riding triumphant into Rome to be proclaimed emperor, Queen Elizabeth I greeting the heroes of the English fleet after the defeat of the Spanish Armada. And yet wouldn’t the quiet, unnoticed passing of life in the backwaters be just as riveting – whether you dropped in on a medieval peasant waking tired as always for a day’s work in the fields or eavesdropped on an eighteenth-century housemaid meeting her lover for a tryst between shifts. Just give me that time ticket and I’ll take it to anywhere!
    But a specific choice is requested. I could go back in time simply for the personal pleasure of witnessing something such as Mozart in concert at first-hand. That would indeed be extraordinary. And yet perhaps ultimately only a little more comes from this than watching a really good DVD. What if stepping back into the past gave you the almost godlike opportunity to change the course of history with the benefit of