摩天轮是一种大型转轮状的机械建筑设施,稳坐于永乐桥之上的“天津之眼”作为世界上唯一一座建在桥上的摩天轮,其巧夺天工和奇思妙想确是当之无愧的“世界第一”.如图,永乐桥摩天轮的直径为
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmn%3E110%3C%2Fmn%3E%3Cmtext%3Em%3C%2Fmtext%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
,到达最高点时,距离地面的高度为
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmn%3E120%3C%2Fmn%3E%3Cmtext%3Em%3C%2Fmtext%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
,能看到方圆
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmn%3E40%3C%2Fmn%3E%3Cmtext%3Ekm%3C%2Fmtext%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
以内的景致,是名副其实的“天津之眼”.实际上,单从高度角度来看,天津之眼超越了曾大名鼎鼎的伦敦之眼而跃居世界第一.永乐桥摩天轮设置有48个座舱,开启后按逆时针方向匀速旋转,游客在座舱转到距离地面最近的位置进舱,转一周大约需要
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmn%3E30%3C%2Fmn%3E%3Cmi%3Emin%3C%2Fmi%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
.游客甲坐上摩天轮的座舱,开始转到
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmi%3Et%3C%2Fmi%3E%3Cmi%3Emin%3C%2Fmi%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
后距离地面的高度为
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmi%3EH%3C%2Fmi%3E%3Cmtext%3Em%3C%2Fmtext%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
,则转到
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmn%3E10%3C%2Fmn%3E%3Cmi%3Emin%3C%2Fmi%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
后距离地面的高度为
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmtext%3Em%3C%2Fmtext%3E%3C%2Fmath%3E)
,在转动一周的过程中,
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi%3EH%3C%2Fmi%3E%3C%2Fmath%3E)
关于
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi%3Et%3C%2Fmi%3E%3C%2Fmath%3E)
的函数解析式为
.