问题 选择题

如图所示,物体自 O点由静止开始做匀加速直线运动,A、B、C、D为其运动轨迹上的四点,测得AB=2m, BC=3m,且物体通过AB、BC、CD所用的时间相等,则下列说法正确的是

A.可以求出物体加速度的大小

B.可以求得CD=4m

C.可以求得OA之间的距离为1.125m

D.可以求得OA之间的距离为1. 5m

答案

BC

题目分析:设物体通过AB、BC、CD所用的时间均为t,由匀变速直线运动的规律相邻相等的时间内位移之差为常数,即可得:物体的加速度a的大小为,因为不知道时间,所以不能求出加速度,故A错误;

根据,可知,故B正确;

因某段时间内的平均速度等于中间时刻的瞬时速度,所以物体经过B点时的瞬时速度为,再由可得OB两点间的距离为,所以O与A间的距离,故C正确,D错误.所以选BC.

单项选择题
单项选择题

A narrowing of your work interests is implied in almost any transition from a study environment to managerial or professional work. In the humanities and social sciences you will at best reuse only a fraction of the material (1) in three or four years’ study. In most career paths academic knowledge only (2) a background to much more applied decision-making. Even with a " training " form of degree, (3) a few of the procedures or methods (4) in your studies are likely to be continuously relevant in your work. Partly this (5) the greater specialization of most work tasks compared (6) studying. Many graduates are not (7) with the variety involved in (8) from degree study in at least four or five subjects a year to very standardized job (9) . Academic work values (10) inventiveness, originality, and the cultivation of self-realization and self-development. Emphasis is placed (11) generating new ideas and knowledge, assembling (12) information to make a " rational " decision, appreciating basic (13) and theories, and getting involved in fundamental controversies and debates. The humanistic values of higher (14) encourages the feeling of being (15) in a process with a self-developmental rhythm. (16) , even if your employers pursue enlightened personnel development (17) and invest heavily in " human capital " —for example, by rotating graduate trainees to (18) their work experiences—you are still likely to notice and feel (19) about some major restrictions of your (20) and activities compared with a study environment.

(3)()

A.hardly

B.scarcely

C.evenly

D.only