As shown in the figure, the escalator is a schematic diagram for transporting passengers. The escalator runs at a constant speed under normal working conditions, and passengers are very safe. However,

As shown in the figure, the escalator is a schematic diagram for transporting passengers. The escalator runs at a constant speed under normal working conditions, and passengers are very safe. However, at 8: 00 on February 8, 2009, 65438+. A, passengers in the process of uniform rise and fall to keep balance, the resultant force is zero; Because of gravity and support, the two forces are balanced, so AB is wrong;

C. In the reverse process of the escalator, passengers first decelerate upward and then accelerate downward, and there is downward acceleration along the inclined plane, which is decomposed into horizontal and vertical acceleration, so people are subjected to the friction of the escalator to the left, so C is correct;

D, in the process of escalator inversion, the passenger's friction on the escalator first increases, then decreases, and finally reaches zero, so D is wrong;

So choose: C.