太阳能汽车是靠太阳能电池提供动力．若某太阳能汽车质量是500kg_爱下问搜题

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问题计算题

太阳能汽车是靠太阳能电池提供动力．若某太阳能汽车质量是500kg，在平直路面上行驶速度最大可达15m/s，行驶过程中所受的平均阻力是车重的0.02倍，轮胎接触地面的总面积是200 cm²，则该汽车在平直路面上以最高速度行驶5min时，（g取10N/kg）

（1）驱动电机提供的牵引力是多少？

（2）太阳能汽车克服阻力做了多少功？驱动电机的输出功率是多少？

（3）该太阳能汽车对水平路面的压强为多大？

答案

（1）驱动电机提供的牵引力是100N

（2）太阳能汽车克服阻力做了多少功？驱动电机的输出功率是1500W

（3）该太阳能汽车对水平路面的压强为

题目分析：解：（1）重力=500kg×10N/kg=5000N

阻力="0.02×5000N=100N"

由题意知，汽车做匀速直线运动，所以F=f=100N

（2）=15m/s×5×60s=4500m

=100N×4500m=4.5×10⁵J

或P=Fv=100N×15m/s=1500W

（3）压力F=G=5000N，S=200cm²=0.02m²

点评：本题通过汽车在水平地面上行驶，考查了重力计算、压强、压力、功率、平衡力等．包含了力学的一些重要计算．综合性比较强．

单项选择题

设有定义语句 int x[6]={2,4,6,8,5,7},*p=x,i;　　要求依次输出x数组6个元素中的值，不能完成此操作的语句是（）。

A．for(i=0;i<6;i++）printf("%2d",*(p++));

B．for(i=0;i<6;i++）printf("%2d",*(p+i));

C．for(i=0;i<6;i++）printf("%2d",*p++);

D．for(i=0;i<6;i++）printf("%2d",(*p)++);

完形填空

There was a little boy      his grandparents on their farm. He was given a slingshot（弹弓）to play with, out in the woods. He        in the woods, but he could never hit the target. Getting a little     , he headed back to dinner. Then, he saw Grandma’s pet duck, so he let it fly, hit the duck in the head, and          it. He was shocked and upset. In       , he hid the dead duck in the woodpile, only to see his sister __   ___.Sally had seen it all,        she said nothing.
      lunch that day grandma said, “Sally, let’s wash the dishes.” But Sally said, “Grandma, Johnny told me he wanted to    in the kitchen today, didn’t you Johnny?” And then she said to him in a(n) _   ___ voice, “Remember, the duck?” So Johnny did the dishes.
Later Grandpa asked if        wanted to go fishing, and Grandma said, “I’m sorry but I need ___   ___ to help make supper.”
Hearing this, Sally said with a smile, “Well, that’s        but Johnny told me he wanted to help.”        the duck, Johnny had to stay and Sally went fishing.
After several days of Johnny doing both his        and Sally’s, he finally couldn’t       it any longer. He came to Grandma and told her that he __   ___ the duck. She knelt down, gave him a hug（拥抱）,and said,“Sweet heart, I know. You see, I was standing at the window and I       the whole thing. But because I love you, I       you. But I was just       how long you would let Sally make a slave of you.”

D．discouraged

B．disappointment

A．the children

C．Remembering

C．congratulated