问题 填空题

清扫路面垃圾的清洁车,能通过吸尘器将路面上的垃圾吸入车内容器中.

(1)清洁车沿街道匀速行驶,在清扫垃圾过程中,车的动能将______(选填:“变大”、“变小”或“保持不变”).

(2)开车上坡前,司机往往加大油门以提高车速,这是为了增大汽车的______能.

(3)如图1是汽车四冲程发动机的______冲程,该冲程是将______能转化为______能.

(4)生活中我们经常看到司机往汽车发动机的水箱里灌水,这是因为水的______大,所以在相同条件下水能带走较多的______,冷却效果好.这是利用______方式降低发动机的内能.

(5)图2是清洁车行驶时,发动机的能量流向图,由图2中的信息,计算该汽车发动机的效率为______.

答案

(1)因清洁车沿街道匀速行驶,车的速度不变,在清扫垃圾过程中,车的质量增加,所以车的动能将变大.

(2)开车上坡前,司机往往加大油门以提高车速,这是为了增大汽车的动能;

(3)由图1可以看出,两气门都关闭,活塞下行,汽缸容积变大,是做功冲程,将高温高压燃气的内能转化为活塞的机械能;

(4)因为水的比热容较大,相同质量的水和其它物质比较,升高相同的温度,水吸收的热量多,所以用水冷却发动机,冷却效果好;这是利用热传递的方式降低发动机的内能;

(5)由图2可以看出,做有用功的能量为6×108J,输入发动机的燃料的总能量为3×109J,

所以热机的效率为η=

W有用
Q
=
6×108J
3×109J
=20%.

故答案为:(1)变大;(2)动;(3)做功;内;机械;(4)比热容;热量;热传递;(5)20%.

阅读理解

Once there was a forest where all the animals lived happily together. One day a family went to spend the day in the forest, and the son left his socks there. After the family left, a bear came by, found the socks, and decided to try them on. They fit so well, and he liked them so much that he wouldn't take them off.

All the animals talked about the bear's new look. Soon, in that forest, there began appearing squirrels in shirts, rabbits in shoes, and even rats (老鼠)  wearing hats! The forest doctor shook his head, telling animals, "This can't be good. Animals don't need clothes!" But no one listened to him. They said he was just out of fashion.

However, it wasn't long before the first results of fashion-fever came. Several times the squirrel caught his shirt on trees, stopping him in mid-jump and sending him falling to the ground from a tree. The rat couldn't go into his hole without taking off his hat first. Even the bear, because of his socks, slipped(滑到) from the river rock and almost killed himself.

When the animals came to see the doctor, he gave them all the same advice, "Take off those clothes before one day they're going to kill you." Those who listened to the doctor's advice stopped having accidents. And the animals realized that they didn't need clothes at all. Starting to wear them had been very dangerous, and they had only done it to make others admire them, and to get attention.

小题1: ______ found the socks and tried them on.

A.The son

B.The bear

C.The rabbit

D.The rat小题2:From the story we can know that______.

A.the family had a good time with the bear

B.the animals didn't like the bear's new look

C.the forest doctor told the animals not to wear clothes

D.the squirrel couldn't go into his hole with his hat on小题3:The underlined sentence "it wasn't long before the first results of fashion-fever came." probably means that_______.

A.soon the animals had a fever because of the clothes

B.soon the animals enjoyed wearing clothes very much

C.soon the animals became healthier in the warm clothes

D.soon the animals had lots of accidents because of the clothes小题4:The story is written to tell us______.

A.helping others is helping yourself

B.we should be careful in the forest

C.things that fit yourself are the best

D.animals must be looked after well

问答题 简答题