问题
填空题
汽车上坡时往往要换低档减速，这是为了______．人骑自行车上坡前往往要加速骑行，这是为了______
山上的公路往往修成盘山S状，这是为了______．
答案
由公式P=Fv得到F=
，汽车功率一定，速度减小，所以牵引力增大；P v
在人和自行车的质量一定时，速度越大，电能越大；
斜面的好处是可以省力．
故答案为：增大牵引力；增大动能；省力．
搜题请搜索小程序“爱下问搜题”
汽车上坡时往往要换低档减速，这是为了______．人骑自行车上坡前往往要加速骑行，这是为了______
山上的公路往往修成盘山S状，这是为了______．
由公式P=Fv得到F=
，汽车功率一定，速度减小，所以牵引力增大；P v
在人和自行车的质量一定时，速度越大，电能越大；
斜面的好处是可以省力．
故答案为：增大牵引力；增大动能；省力．
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| 1 all the things we eat and drink, water is the 2 important. Not 3 people understand this, but it is quite true. The human body can go 4 food for a long time, but two 5 three days without water usually make people 6 . Many people don't understand how 7 water the human body needs 8 well and many people don't drink enough, especially in hot weather. More people drink when they are thirsty. They often need more water, especially when they take exercise. A man's body is 65 to 75 percent water. If we don't have 9 water, we feel 10 and may become ill. Do you know what the best drink is? | ||||
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