题目

 (山东省滨州市2007届高三第四次模拟考试C篇) Hello, children and parents. Thank you all for coaling to this meeting. I’d like to start by confirming that we will receive some money from the government for our school trip to Indonesia. We will receive approximately $ 1,300 per child, which will reduce the overall cost to you. Now that we are sure to get the money, it is time to do some serious planning. We are sure that the trip will be very exciting for the children, especially if they have not traveled overseas before. There are many benefits to having some exposure to7．如图所示，一根细线下端拴一个金属小球A，细线的上端固定在金属块B上，B放在带小孔的水平桌面上，小球A在某一水平面内做匀速圆周运动．现使小球A改到一个更低一些的水平面上做匀速圆周运动（图上未画出），金属块B在桌面上始终保持静止，则后一种情况与原来相比较，下面的判断中正确的是（　　）A．金属块B受到桌面的静摩擦力变大B．金属块B受到桌面的支持力变小C．细线的张力变大D．小球A运动的角速度减小