题干

小明用如图所示的装置探究小车沿斜面下滑时速度的变化.

⑴小明在斜面中点处放一金属片,用停表记下小车从斜面顶端滑下至撞击金属片的时间t1,并用刻度尺量出小车通过的距离s1

⑵小明把金属片放在斜面终点,在斜面中点位置释放小车,测出小车下滑到底端撞击金属片的时间t2和这段时间内小车通过的距离s2

⑶用测得的数据求出各段的平均速度.小明发现v1=v2,于是得出结论:小车从斜面顶端滑至底端做匀速直线运动.

你认为小明的实验过程妥当吗?____ 。为什么?____

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