题干

某同学通过以下步骤测出了从一定高度落下的排球对地面的冲击力:将一张白纸铺在水平地面上,把排球在水里弄湿,然后让排球从规定的高度自由落下,并在白纸上留下球的水印.再将印有水印的白纸铺在台秤上,将球放在纸上的水印中心,缓慢地向下压球,使排球与纸接触部分逐渐发生形变直至刚好遮住水印,记下此时台秤的示数即为冲击力的最大值.下列物理学习或研究中用到的方法与该同学的方法相同的是

A:建立“合力与分力”的概念

B:建立“点电荷”的概念

C:建立“瞬时速度”的概念

D:研究加速度与合力、质量的关系

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答案(点此获取答案解析)

A

同类题5

阅读下面文章,然后从文后所给的A—F选项中选择正确的小标题,将其序号填入题中。其中有一项是多余选项。

A. Animals on the Road

B. Keep Left

C. Crossing “Give Way” Rule

D. Traffic information

E. One Lane Bridges

F. Seatbelts

    Driving around New Zealand may be different from your own country. It's necessary for you to know more traffic information if you are traveling to New Zealand. Here are some tips to help you drive safely in New Zealand.

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    In New Zealand, traffic goes on the left side of the road and the driver sits on the right of the car. You should be careful to the left side while turning.

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    In general, driving in New Zealand is stress free. The only major difference is the “give way to the right'rule. This meant that if you were turning left, you had to give way to vehicles turning right into the same lane. 

    It is important to note that anyone behind a give way sign must give way to any cars on roads. Failure to give way will result in a $ 150 fine.

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    Many roads in New Zealand have one lane bridges on them. At one lane bridges, cars traveling in one direction must give way to cars going in the other one.

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    Pay more attention to farm animals on the road, especially in the countryside. On seeing them, you should stop and let the animals go past you or follow the farmer's instruction.

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    The seatbelts must be worn by the drivers. If you are caught not wearing your seatbelts, you will be fined.

All the tips above are necessary for a stranger to New Zealand.