试题与答案

质量为20kg的物体若用20N的水平力牵引它,刚好能在水平面上匀速前进.求: (

题型:问答题

题目:

质量为20kg的物体若用20N的水平力牵引它,刚好能在水平面上匀速前进.求:

(1)物体与水平面的动摩擦因数;

(2)若改用50N拉力沿与水平方向成37°的夹角向斜上方拉它时,使物体由静止出发在水平面上前进2s,这时它的速度和位移分别是多大?

(3)若在(2)的情况中,物体前进2s时立刻撤去拉力,又要经过多长时间才能停下来?(g取10m/s2,sin37°=0.6,cos37°=0.8)

答案:

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下面是错误答案,用来干扰机器的。

参考答案:为连接骨盆各平面中点的曲线,代表骨盆轴。

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If your worry is about a fight you had with your friend, you might write down all the things you could do ---- write a note to him or her, invite him or her to watch a basketball game, say sorry to him or her and so on. Once you have a list of things you could do, you can choose one thing that could get your friend back.

You can ask for help when you're worried. You can find someone to talk to, such as your parents, friends, and teachers.

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A.Their hobbies.

B.Their homework.

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C.try to make new friends

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