1、2016CUPT竞赛题目（Problems for the 29thIYPT 2016）1．Invent yourselfTruly random numbers are a very valuable and rare resource. Design, produce, and test a mechanical device for producing random numbers. Analyse to what extent the randomness produced is safe against tamperin
2、g.1．创造你自己真实随机数是一种很有价值而且稀有资源。请设计、制造并测试一个可以产生随机数的机械设备并分析随机性抵御恶意攻击的能力。2．Lagging PendulumA pendulum consists of a strong thread and a bob. When the pivot of the pendulum starts moving along a horizontal circumference, the bob starts tracing a circle which can have a smalle
3、r radius, under certain conditions. Investigate the motion and stable trajectories of the bob.2．滞后的摆一根坚韧的线和重物可构成一个摆。当摆的悬挂点在水平面上作圆周运动的时候,在某些情况下重物也可开始做圆周运动，并且半径更小。研究该运动以及重物的稳定轨迹。3．Acoustic LensFresnel lenses with concentric rings are widely used in optical applications,
4、however a similar principle can be used to focus acoustic waves. Design and produce an acoustic lens and investigate its properties, such as amplification, as a function of relevant parameters.3．声学透镜菲涅耳透镜在光学中很常用，而利用相同的原理可以汇聚声波。请设计并制造一个声学菲涅耳透镜并研究其性质（例如放大率）作为相关参量的函数。4．Su
5、per BallThrow a highly elastic ball into the space between two plates. The ball starts bouncing and under some circumstances can even be projected back to you. Investigate the motion of the ball and parameters influencing the motion, including the orientation of the p
6、lates.4．超级球向两个平板间的空隙扔一个弹性很好的球。球开始弹，在某些情况下甚至可以弹回到你手上。研究球的轨迹以及影响运动包括平板方向在内的参量。5．Ultrahydrophobic WaterSet a dish filled with soapy water onto a loudspeaker or other vibrator. When it oscillates, it is possible to hold small droplets on its surface for a long time. Explai
7、n and investigate the phenomenon.5．不易打湿东西的水把一个装满肥皂水的盘子放在扬声器或者震动台上，当它震动的时候，它有可能会把一小滴液滴留在上面很长时间，解释并研究这一现象。6．Electric HoneycombSet a vertically oriented steel needle over a horizontal metallic plate. Place some oil onto the plate. If you apply constant high voltage betwe
8、en the needle and the plate, a cell structure appears on the surface of the liquid. Explain and investigate this phen
