A:23
B:2
C:4
D:6
(2015•广东佛山)________ I live in a safe community, I still feel a little worried when I go out at night.
弹簧测力计拉着重50N的物体在水平面上以0.3m/s的速度作匀速直线运动,弹簧测力计的示数是5N;现在使物体以0.6m/s的速度在原来的水平面上作匀速直线运动,物体受到的摩擦力为( )