如图甲为研究“转动动能与角速度关系”的实验装置示意图，现有的器材为：竖直方向的转盘（转轴水平），带铁夹的铁架台、电磁打点计时器（接交流电的频率为50 Hz）、纸带、重锤、游标卡尺、天平。回答下列问题：
（1）如图乙所示，用20分度的游标卡尺测得圆盘的直径d为___________cm；
（2）将悬挂铁锤的纸带穿过打点计时器后，绕在转盘边缘上，纸带一端固定在转盘上，使得转盘与纸带不打滑，设纸带厚度不计，打开电源，释放重锤，打点计时器打出的纸带如图丙所示，O、A、B、C……各点为连续打出的点迹。则由图丙中数据可得，打下点迹D时，圆盘转动的角速度为ωD＝___________rad/s（保留三位有效数字）；
（3）下表为各点对应的转动动能Ek和角度速ω的值，请你猜想转动动能Ek和角速度ω满足的关系式为Ek＝___________（填准确的表达式）。
（1）5.020或5.025
（2）15.9
（3）6.25×10－5ω2 J
About a week ago, my 4yearold cousin and I were playing basketball at our local park. The__31__was warm, and many other children were outside__32__. As we played, I noticed a small group of boys__33__a smaller, skinnier, and possibly younger boy. They were calling him names and__34__pushed him to the ground and__35__dirt in his face. When I saw that, I grabbed my__36__by the hand and walked over to the__37__. I stepped__38__them and the younger boy, and asked them__39__what this boy had done deserved__40__they were doing to him. They all__41__silently for a moment, and then the most amazing thing __42__：one of the boys who hadn't said anything since I__43__stepped around the younger boy and helped him off the__44__and then apologized. He offered to let him play with them，__45__the boy quietly said “thank you” and refused, and then left there. As I looked around, I__46__that there were dozens of other people at the park—some of them were__47__with children of their own—but no one else had stopped to help this boy. I felt__48__that the one of the boys was brave enough to stand up against his friends to help someone__49__， but I felt sad that no one else had even taken a second__50__. I couldn't help but think that those parents at the park would want someone to help their child in that situation, and yet they did nothing but stood by.
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