题干

学以致用是我们学习科学的目的之一,要求我们能够对日常生活中某些简单的现象做出科学的解释.道路交通安全法规定:严禁汽车超载超速.一位司机驾驶大货车在某路段行驶时,由于超速被警察拦停,警察对司机说:“先生,刚才你的车速为70km/h,超速了.”这位司机不满地说:“小客车的限速为80km/h,而大货车的限速却为60km/h,为什么小客车的限速比大货车限速大?不合理!”.请你从两个不同角度向司机作出科学解释?
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答:物体的动能与物体的质量和速度有关,在速度一定的情况下,物体质量越大动能越大,所以大货车的限速比小客车大限速小;

当物体的动能相等,则质量大的物体,速度要小一些.因为大货车的质量大于小车的质量,所以大货车的限速应小于小客车的限速.

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    Millions of Chinese have been playing a mobile game called Travel Frog recently. You play as the “mother” of a frog who lives alone and enjoys traveling. You need to prepare food and tools for his trips. The frog will send you postcards while he is away.

    The game's popularity may have something to do with how lonely people are these days, according to the Xinhua News Agency. Many players have said that the lonely frog is just like them. But playing with the frog helps them forget their loneliness for a short time.

    Loneliness seems to be a common problem today. According to the Guardian, about 40 percent of American adults say they're lonely. And in the UK, about one in five people in the country are “always or often lonely”, The Telegraph reported.

    This might be why the UK government declared (宣布) the country's very first “Minister of Loneliness” (孤独大臣) in January. The minister's job is to find ways to help UK citizens feel less lonely. The minister's office will provide more money for activities that connect people together.

    This loneliness problem may be partly due to social media. When we see pictures of friends having fun or posting selfies (自拍) without us, we may compare their “perfect” lives with our own and feel inferior (较差的) and lonely.

    But we should remember that no one is destined (注定) to be lonely. As UK poet John Donne once wrote, “No man is an island, entire of itself; every man is a piece of the continent (陆地), a part of the main.”

    Tips to get rid of loneliness

    Sing your favorite songs.

    Connect with a friend.

    Do something creative, such as drawing a picture.

    Imagine some place you'd like to visit, like a fun gathering or a sporting event.