题干

小明得到一个玩具吹镖(由一个细长筒和金属镖头组成),想试着用它去射地上的目标.他把重为G的小镖头以一定速度正对着目标A点吹出,如图.忽略镖头运动时所受的空气阻力,下列关于镖头能否射中A点的预测中,正确的是(    )

A:一定能够射中A点

B:一定射在A点右侧

C:一定射在A点左侧

D:控制速度大小,以上都有可能

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答案(点此获取答案解析)

B

同类题5

    Is getting a black belt(腰带) on your life's to-do list? Then this elderly woman in San Francisco just might be your hero.
    Just two years before her 100th birthday, Sensei Keiko Fukuda has become the first woman to achieve a tenth-degree black belt --- the highest rank in Judo (柔道). Fukuda is now one of only four living people who have earned the tenth-degree black belt. Throughout history, only 16 people have ever achieved this honor.
    Fukuda began practicing Judo in 1935 and is the only surviving student of its founder, Kano Jiguro.
At her teacher's requirement, she learned English to help spread Judo internationally.
    During a time when getting married, building a family and becoming a housewife were the norms(行为标准),Fukuda broke from tradition, continuing Judo instead of getting married.
    “All I did was Judo ... This was my marriage,” Fukuda replied tearfully to the San Francisco Chronicle. “This is when my destiny (命运) was set. I just imagined how long the road would be.”
    She described the Jiguro's school as “old-fashioned and sexist(性别歧视的) about belts and ranks”. In fact, an edict(法令) that prevented women from achieving any higher than a fifth-degree black belt kept Fukuda at that level for 30 years. She finally got the sixth degree in 1972 when a women's division(分部)was created.
    Fukuda thinks Judo and her life to be “gentle, kind and beautiful, yet firm and strong, both mentally and physically”. Fukuda says this kind of beauty is not external(外在的). She explained. “I believe this inner beauty is true beauty… All my life this has been my dream.”
    Her dream was turned into reality, and the 98-year-old Sensei Keiko Fukuda continues to teach Judo three times a week at a women’s Judo training center.