2 1. as shown in the figure, fix ONe end o of the soft light rope on, tie a heavy object at a certain point m in the middle, and pull the other end n of the rope by hand. Initially, OM is vertical and MN is straight, and the included angle between OM and MN is α (α >: π/2). Now slowly pull the weight to the upper right, keeping the included angle α unchanged. When OM is pulled from vertical to horizontal (AC)
A. the tension on Mn increases gradually.
B. the tension on Mn first increases and then decreases.
The tension on com is gradually increasing.
The tension on D.OM first increases and then decreases.
22.(5 points)
In order to study the linear motion of the car on the table, a research team used a self-made "drip timer" to measure the time. Before the experiment, fix the timer beside the car, as shown in Figure (a). Keep the table level and gently push the car with your hands. During the movement of the car, the drip timer drops small water drops at equal intervals, for example, (b) records the positions of six consecutive water drops on the table. (It is known that the drip timer drops 46 small water drops every 30 s).
(1) As can be seen from Figure (b), the car moves on the desktop in _ _ _ _ _ _ (fill in "from right to left" or "from left to right").
(2) According to the data in Figure (b), the students in this group judge that the car is driving at a constant speed. When the car moves to point A in Figure (b), the speed is _ _ _ _ _ _ _ m/s and the acceleration is _ _ _ _ _ _ m/s2. (The results all keep 2 as a valid number)
The answer to this question is
(1) From right to left
(2)0.33 0.038
The above are some questions and answers of a comprehensive science examination paper in the national college entrance examination for reference only.