题目

水平地面上的物体质量为1kg，在水平拉力F=2N的作用下从静止开始做匀加速直线运动，头2s内物体的位移为3m．则物体运动的动摩擦因数大小为（                                                                  ）            A． 0.05        B．                      0.03                     C．  0.02 D． 0.015                                                            Liu Yu wants to be a_ __．But his parents won’t allow him to train as much as he want.A．basketball player B．football playerC．Professional runner D．famous scientist