Two Trips

Jack brought a small plane and began to fly it． He soon became excited and made his plane all kinds of tricks．

Jack had a friend，named Tom． One day Jack said to him，“I will pick you up in my plane．““I will be glad to．'answered Tom． They went up，and Jack flew around for half an hour and did all kinds of tricks in the air． Then they came down． Tom was to be back safely，and said to Jack，“Well，Jack，thank you very much for those two trips in your plane．“Jack was very surprised and asked，“Two trips？““Yes，my first and my last．'an﹣swered Tom．

根据上文填表

我们生活中的很多现象往往蕴藏着地理知识．下列现象中，与地球自转有关的是（    ）

已知平面直角坐标系中，曲线C₁的参数方程为 $\{\begin{array}{l}x=\sqrt{3}+3cox\theta \\ y=-1+3\sin \theta \end{array}$ （φ为参数），以原点为极点，x轴的正半轴为极轴建立极坐标系，曲线C₂的极坐标方程为ρ=2cosθ．

（Ⅰ）求曲线C₁的极坐标方程与曲线C₂的直角坐标方程；

（Ⅱ）若直线θ= $\frac{\pi }{6}$ （ρ∈R）与曲线C₁交于P，Q两点，求|PQ|的长度．