标题: （求助）我知道这里有人英语学得很好 [打印本页] 作者: 切风40.83 时间: 2009-9-30 23:48 标题: （求助）我知道这里有人英语学得很好 Analyse（Explain how you know where each of these points is.）
Before I did this experiment, I made a mark on the ramp. I did not released the car before it pass the mark. The graph started when the car pass the mark. So I started pushing the car before the “zero” and stopped pushing at “zero”. From the acceleration graph, the acceleration has changed at “2”. It caused by the direction of the net force has changed at that time. As we all know, the net force always against the object. So point “2” is the top. At point 4.2, the car stopped. So the point 4.2 is the end point.
（Explain the second question.）
The acceleration was different between it gone up and gone down. When it gone up, the acceleration was mg*sin(A)+ net force. When it gone down, the acceleration was mg*sin(A)- net force. So the absolute value of acceleration of gone up was larger than the one of gone down. Both the distance of gone up and gone down is same.
Technically, the acceleration is mg*sin(A) at that moment(stopped at the top). The graph did not show the acceleration at that moment.
When the cart was at the top, the velocity would be very close to zero and it also would be positive in the next instant. [(lim x→0+)x]
以上是我的物理作业，明天要上交。帮我看看有什么错误。谢谢！作者: 切风40.83 时间: 2009-9-30 23:53
忘记解释下具体情况了。
这是个实验报告，实验是用多普勒雷达侧斜面上的小车的运动数据。
我用手把小车推上斜面，在小车到达标记处之前释放，当小车经过标记处时，我的助手打开位于斜面顶端的雷达，电脑开始收集数据。
小车到达顶端后回滑到底部作者: pig884 时间: 2009-10-1 12:15
你在国外英文应该是这里最好的吧？作者: 切风40.83 时间: 2009-10-2 00:23
不是啊，至少有两个比我好的
一个是 飞车
还有一个我忘了作者: pig884 时间: 2009-10-8 20:53
