问题 实验题

乙同学采用如图所示的装置进行了有关“动能定理”探究的实验。

a.按图把实验器材安装好,不挂配重,反复移动垫木直到小车能够做匀速直线运动;

b.把细线系在小车上并绕过定滑轮悬挂质量为100g的配重。接通电源,放开小车,电火花计时器在被小车带动的纸带上打下一系列点。从某点A开始,此后在纸带上每隔4个点取一个计数点,依次标为B、C、D……;

c.测量出B、C、D、……各点与A点的距离,分别记为x1、x2、x3……;

d.用配重受到的重力分别乘以x1、x2、x3……,得到配重重力所做的功W1、W2、W3……;(重力加速度g=9.80m/s2

e.求出B、C、D、……各点速度的大小,分别记为v1、v2、v3……,再求出它们的平方v12、v22、v32……;

f.用纵坐标表示速度的平方v2,横坐标表示配重重力所做的功W,作出v2-W图象,并在图象中描出(Wi,v)坐标点,再连成图线。(以下计算保留到小数点后两位)

(1)若该同学得到的v2-W图象如图乙所示。通过图象可知W与v2的关系是______________

(2)通过图象可求出,小车的质量M=_________kg。(保留到小数点后两位)

(3)关于该实验,下列说法正确的________。

A.电火花计时器应用4~6 V的直流电源供电

B.电火花计时器应用4~6 V的交流电源供电

C.在步骤d中,该同学测得x4=40.00 cm,则配重重力所做的功W4=0.39 J

D.通过图象可知,打A点时对应小车的速度v0=0.50 m/s

答案

(1)成正比

(2)0.30

(3)CD

阅读理解

根据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

When we think about happiness, we usually think of something extraordinary, a pinnacle (顶点) of sheer (纯粹的) delight. And those pinnacles seem to get rarer the older we get.

 1   I remember playing police and robbers in the woods, getting a speaking part in the school play. Of course, kids also experience lows, but their delight at such peaks of pleasure as winning a race or getting a new bike is unreserved.

For teenagers, or people under 20 the concept of happiness changes.   2   I can still feel the pain of not being invited to a party that almost everyone else was going to. I also remember the great happiness of being invited at another event to dance with a very handsome young man.

In adulthood the things that bring great joy—birth, love, marriage—also bring responsibility and the risk of loss.   3   For adults, happiness is complex.

 4   But I think a better definition of happiness is “ the ability to enjoy something”. The more we can enjoy what we have, the happier we are. It's easy to overlook the pleasure we get from loving and being loved, the company of friends, the freedom to live where we please, even good health.

While happiness may be more complex for us, the solution is the same as ever. Happiness isn't about what happens to us; it’s the ability to find a positive for every negative, and view a difficulty as a challenge.   5  

A.Love may not last; loved ones die.

B.For a child, happiness has a magic quality.

C.Happiness is the meaning and the purpose of life.

D.Being happy doesn’t mean that everything is perfect.E. The dictionary defines “happy” as “lucky” or “ fortunate”.

F. It's not wishing for what we don't have, but enjoying what we do possess.

G. Suddenly it’s conditional on such things as excitement, love, and popularity.

单项选择题