问题 问答题

2013年1月1日,史上最严交规正式实施.其中,闯黄灯将被扣6分这一条备受争议.网民指出,驾驶员从发现黄灯到立即刹车制动需要一段时间,这段时间叫反应时间,在这段时间里汽车通过的距离叫反应距离.从操纵制动器,到汽车完全停止,汽车又前进一段距离,这段距离叫制动距离.若一辆汽车在公路上以40km/h的速度匀速行驶,看到黄灯后立即刹车.问:

(1)反应距离是多少?

(2)为避免黄灯亮起时越过停车线,当汽车以40km/h的速度匀速行驶时,驾驶员必须使自己驾驶的汽车与停车线保持一定的距离,这一距离至少要大于多少米?

(3)为了避免闯黄灯请你结合所学物理知识,给驾驶员提出另外一条合理化的建议.

速度/km•h-1反应时间t/s制动距离/m
400.6308
500.64813
600.66020
800.67534
1000.68454

答案

(1)在反应时间内汽车行驶的速度不变,

∵v=

s
t

∴以40km/h的速度匀速行驶时的反应距离:

s=vt=

40
3.6
m/s×0.630s=7m;

(2)由表可知,当汽车以40km/h的速度匀速行驶时的制动距离为8m,

为避免黄灯亮起时越过停车线,则汽车与停车线保持的距离:

s=s+s=7m+8m=15m;

(3)为了避免闯黄灯可以减小车行驶的速度等.

答:(1)反应距离是7m;

(2)为避免黄灯亮起时越过停车线,当汽车以40km/h的速度匀速行驶时,自己驾驶的汽车与停车线的距离至少为15m;

(3)降低车速等(合理即可).

阅读理解

阅读理解。

     In 1961, a man found a strange cat on his farm in Scotland. The cat's ears were folded, bent forward,

on its head. In fact, this was a new kind of cat. People named it the "Scottish Fold (苏格兰折耳猫)".

     The Scottish Fold has a round head and large eyes. Its neck and legs are short, which makes it look very

cute. Interestingly, all the Scottish Folds are born with straight and unfolded ears. And when they are growing

up day by day, some cats' ears will begin to fold. So, the Scottish Fold comes in two types: folded ears and

straight ears.

     Besides, there is a nickname for the Scottish Fold. It is the "Messenger of Peace". Why? Because the Folds

are sweet and friendly animals. They can get along well with other cats. And unlike some other cats, they can

even get along well with dogs! In many different environments, such as at a noisy house, or in a cat show,

you can see them playing with other animals happily. Well, when you come to a new school, do you think it's

difficult to adapt to the new environment? Perhaps you can learn from the Scottish Fold. That is: always be

sweet and friendly to others.

1. Tie Scottish Fold ________.

A. is born with folded ears

B. is born with straight ears

C. always has folded ears

D. always has straight ears

2. What does the Scottish Fold look like?

A. It has a round head and large eyes.

B. Its neck and legs are short.

C. It looks very cute.

D. All above.

3. Why are the Scottish Folds named the "Messenger of Peace"?

A. Because their ears are folded.

B. Because they look very cute.

C. Because they can get on well with other animals.

D. Because they can stay at a noisy house or in a cat show.

4. According to the passage, what is the writer's suggestion to us when we are in a new environment?

A. We should have a nickname.

B. We should learn from the cats.

C. We should get along well with dogs.

D. We should always be sweet and friendly to others.

单项选择题