题干

关于摩擦力,下列说法中正确的是(   )

A:相互压紧的粗糙物体间一定存在摩擦力

B:相互接触的粗糙物体间的压力增大,摩擦力也一定增大

C:静止的物体不可能受到滑动摩擦力的作用

D:摩擦力方向可能与物体运动的方向相同

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答案(点此获取答案解析)

D

同类题3

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    A psychologist walked around a room while teaching stress management to the audience. As she raised a glass of water, everyone expected they'd be asked the “half empty or half full” question. Instead, with a smile on her face, she inquired. “How heavy is this glass of water?”

    Different answers are called out from the audience.

    She replied, “The absolute weight doesn't matter. It depends on how long I hold it. If I hold it for a minute, it's not a problem. If I hold it for an hour, I'll have an ache in my arm. If I hold it for a day, my arm will feel numb and paralyzed. In each case, the weight of the glass doesn't change, but the longer I hold it, the heavier it becomes.”

    She continued. “The stresses and worries in life are like that glass of water. Think about them for a while and nothing happen. Think about them a bit longer and they begin to hurt you. And if you think about them all day long, you will feel paralyzed and be incapable(无能力的)of doing anything.”

    It's important to remember to let go of your stresses. As early in the evening as you can, put all your burdens down. Don't carry them through the evening and into the night.

    Remember to put the glass down!”

    Comments:

    Aye Chan Aung-February 27, 2017 at 11:37am

    Short but valuable! It clearly teaches me how to deal with stresses.

    Nelson Malicdem-February 28, 2017 at 8:23 pm

    Wow! Thank the author and the one who submitted the article. I am experiencing a challenge when I read this. It gives me peace. What exactly is in the article is what I am doing. My burden actually paralyzes me without my knowing it. I put down the glass of water that I am holding. Thank you so much!