河北省大学生物理竞赛题目

附件1：

2014年第一届河北省大学生物理竞赛（实验部分）竞赛题目

复赛题目（五选四）：

1. Invent yourself

It is known that some electrical circuits exhibit chaotic behaviour. Build a simple circuit with such a property, and investigate its behaviour.

自己创造

据了解，一些电路表现出混沌行为。构建一个具有这样属性的简单电路，并研究其行为。

2. Twisted rope

Hold a rope and twist one end of it. At some point the rope will form a helix or a loop. Investigate and explain the phenomenon.

扭曲的绳

握住绳子扭它的一端。在绳索上的某一点将形成螺旋线或圆环。调查解释这样的现象。

3. Loaded hoop

Fasten a small weight to the inside of a hoop and set the hoop in motion by giving it an initial push. Investigate the hoop’s motion.

载物的环

在一个环的里面固定一个小重物，给环一个初始推力使其运动。研究环的运动。

4. Coefficient of diffusion

Using a microscope, observe the Brownian motion of a particle of the order of micrometre in size. Investigate how the coefficient of diffusion depends on the size and shape of the particle.

扩散系数

利用显微镜按微米大小的顺序观察微粒的布朗运动。研究扩散系数是如何取决于微粒的大小和形状的。5. Oil stars

If a thick layer of a viscous fluid (e.g. silicone oil) is vibrated vertically in a circular reservoir, symmetrical standing waves can be observed. How many lines of symmetry are there in such wave patterns? Investigate and explain the shape and behaviour of the patterns.

油星星

如果一层厚厚的粘性流体（如硅油）在一个圆形的水槽里上下振动，可以观察到对称驻波。在这样的波图案中有多少条对称的线？研究并解释图案的形状和行为。

决赛题目：

1. Pot-in-pot refrigerator

The ‘pot-in-pot refrigerator’ is a device that keeps food cool using the principle of evaporative cooling. It consists of a pot placed inside a bigger pot with the space between them filled with a wet porous material, e.g. sand. How might one achieve the best cooling effect?

“罐中罐冰箱”

这一个依据蒸发冷却的原理让食物保鲜的装置。它包括一个大容器、里面的小容器。它们之间的空间内用湿的多孔材料填充，例如沙子。问怎么能达到最佳的散热效果？

2. Rubber motor

A twisted rubber band stores energy and can be used to power a model aircraft for example. Investigate the

properties of such an energy source and how its power output changes with time.

橡胶电机

扭曲的橡皮筋存储着能量，例如可以用于驱动飞机模型。调查这样的能量来源的属性及其功率输出随时间的变化。

3. Magnetic brakes

When a strong magnet falls down a non-ferromagnetic metal tube, it will experience a retarding force. Investigate the phenomenon.

磁力刹车

当一个强磁铁从非铁磁性金属管内降下来时，它会经历一个阻滞力，研究这个现象。