问题 问答题

某中学物理课上,为了探究滑动摩擦力的大小与哪些因素有关,同学们提出了两个方面的猜想.

A、滑动摩擦力的大小可能与接触面之间的压力有关

B、滑动摩擦力的大小可能与接触面的粗糙程度有关

可以选用的实验器材有:水平桌面、有挂钩的长方体木块、玻璃板、毛巾、砝码、细线、弹簧测力计等.

经过讨论,大家准备首先检验第一个(A)猜想;

(1)请你选用上述器材(可以选用其中几个,也可以自己另行确定需要的设备)设计一个实验方案,探究滑动摩擦力的大小是否与接触面之间的压力大小有关.

请写出你设计的实验方案(可以画示意图帮助描述)

1你准备选用的器材有:

2你设计的实验探究步骤是:(用适当的字母表示被测的物理量)

A、______B、______

(2)请你预测:根据实验现象,可能会得出什么结论?

答案

(1)①弹簧测力计拉动有挂钩的长方体木块在水平桌面上运动,弹簧测力计显示拉力大小,要使滑动摩擦力等于拉力大小,木块要进行匀速直线运动,探究滑动摩擦力大小跟压力关系,控制水平桌面不变,通过砝码来改变压力大小,所以选择器材:水平桌面、有挂钩的长方体木块、砝码、弹簧测力计.

②实验步骤:A:将弹簧测力计挂在长方体木块上,在水平桌面上通过弹簧测力计沿水平方向拉动长方体木块匀速直线滑动,读出弹簧秤示数F1

B:在长方体木块上加一些砝码,再一次在水平面上通过弹簧测力计沿水平方向拉动长方体木块进行匀速直线滑动,读出弹簧秤示数F2

(2)当F2=F1,则滑动摩擦力的大小与接触面之间的压力无关.

当F2≠F1,则滑动摩擦力的大小与接触面之间的压力有关.

故答案为:(1)①水平桌面、有挂钩的长方体木块、砝码、弹簧测力计;

②A:将弹簧测力计挂在长方体木块上,在水平桌面上通过弹簧测力计沿水平方向拉动长方体木块匀速直线滑动,读出弹簧秤示数F1

B:在长方体木块上加一些砝码,再一次在水平面上通过弹簧测力计沿水平方向拉动长方体木块进行匀速直线滑动,读出弹簧秤示数F2

(2)如果F2=F1,则滑动摩擦力的大小与接触面之间的压力无关;

如果F2≠F1,则滑动摩擦力的大小与接触面之间的压力有关.

完形填空

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Making friends is a skill. Like most skills, you can improve it if you are patient. If you want to meet people and make friends, you must be willing to take action. You must first go where there are people. You won't make friends staying home a      .

Joining a club or a group, talking to those who like the same things as you do is much e     . Or join someone in some activities.

Many people are n    when talking to new people. After all, meeting strangers means seeing  the unknown. And it's human nature to feel a bit unpleasant about the unknown. Most of fears about d     . with new people come from doubts(怀疑) about ourselves. We imagine other people are judging us-finding us too tall or too short, too this or too that. But don't forget that they must be feeling the s     way. Try to accept yourself as you are, and try to make others feel at home.  You'll all feel more c     .

Try to be brave even if you don't feel that way when you e   a room full of strangers. Walk  tall and straight, look d    at other people and smile.

If you see someone you'd like to speak to, say something. Don't w     for the other person to start a conversation(对话).

Just meeting someone new does not mean that you'll make friends with that person. Friendship is based on mutual(相互的)likings and“give and take”.It takes time and effort(精力)for us to d    friendship. And there are things that stop a new friendship from growing.

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