【单选题】Consider an object on a rotating disk a distance r from its center, held in place on the disk by static friction. Which of the following statements is NOT true concerning this object?
A.
If the angular speed is constant, the object has a zero acceleration.
B.
The object has a tangential acceleration only if the disk has an angular acceleration.
C.
The object always has a centripetal acceleration except when the angular speed is zero.
D.
If the angular speed is constant, the speed of object is also constant.
【判断题】挤塑主要用于酚醛树脂、尿醛树脂、不饱和聚酯树脂等。
【简答题】AT89S51的I/O口中,P0口在外接LED时,必须提供( ),它在单片机外扩RAM和I/O接口芯片时,作为分时复用的( )总线口使用,( )口作为高8位地址总线使用,( )口具有第二功能。
【判断题】Phillip is surprised at the number of applications they received
【简答题】凸轮机构的应用场合是什么?凸轮机构的组成是什么?