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细心观察一下你会惊奇地发现,在我们生活的各个角落中,几乎都有摩擦力的身影.它可是一种非常特别的力哦!特别之一,它有时候是阻力,比如拉着行李车在路面上前行,车轮与地面间的摩擦力是你前进的阻力,甚至能让你累得汗流浃背;有时候却是动力,比如人走路就是依靠地面对鞋底的摩擦力.特别之二,当条件发生改变时,摩擦力的大小是可以改变的.比如你骑自行车分别经过一段凹凸不平的土路和平整光滑的水泥路面时,尽管你和自行车对地面的压力没有改变,但是你的感觉却是明显不一样的,土路上脚蹬车很费劲,水泥路上脚蹬车很轻松.特别之三,在看起来差不多的情境中,它有的时候存在,有的时候却不存在.比如随着水平输送带匀速前进的物体与输送带之间没有摩擦力,随着倾斜输送带匀速上升的物体与输送带之间却有摩擦力.特别之四,摩擦力有时是有害的,有时却又是有益的.比如手与自行车把之间的摩擦是有益的,能帮助
You will be surprised to find out that in almost every corner of our lives, there is almost friction figure, but it is a very special force Oh! One of the special, it is sometimes resistance, such as pulling a luggage car On the road ahead, the friction between the wheel and the ground is your resistance to progress, and even make you tired sweat; sometimes it is power, such as walking is to rely on the friction facing the sole.Special, When the conditions change, the size of the friction can be changed.For example, you ride a bike through a rugged dirt road and a smooth cement road, although you and the bike on the ground pressure has not changed, but you feel Is obviously not the same, on the dirt road pedaling car is very laborious, easy on the concrete road pedaling car .Third, in almost the same situation looks, it sometimes exists, sometimes does not exist .For example, with the There is no friction between the horizontal conveyor belt and the conveyor belt, and there is friction between the conveyor belt and the uniform rising conveyor belt. In particular, the friction force is sometimes harmful But is advantageous friction between the hands, such as the bicycle is beneficial, can help