题干

修建大桥在水下施工时,要向江中沉放大量的施工构件,假设一边长3m的正方体构件被缓缓吊入水中(如图甲所示)在沉入过程中,其下表面到水面的距离为h,随着h的增大,钢绳拉力F、物体所受浮力F浮的变化如图乙所示.则以下说法正确的是(  )

A:该正方体的质量是2.7×104kg

B:该正方体的密度是2×103kg/m3

C:图线①反映了浮力随时间变化情况

D:由图可知浮力随深度增加而增大

上一题 下一题 0.0难度 选择题 更新时间:2016-09-13 10:26:51

答案(点此获取答案解析)

B

同类题4

根据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

    Winter is a really fun time of the year—it's great to have snowball fights and build snowmen. ____ When it's cold outside and you're not prepared, you can feel uncomfortable. Lucky for you, learning how to stay safe is not difficult.

    ____Wearing thick clothes is the best way to stay warm in the cold. Depending on where you live and how cold it is, some kids may need more clothes, some less.

    Take that hat. You maybe wear a large overcoat and ready to go, but are you forgetting something?____You'll stay much warmer with a hat than without one—tons of body heat escapes right from your head.

    Drink up. Sounds like advice for hot weather, not cold weather, right?____When you're outside in the cold and breathing hard, your body loses a lot of water through your breath. And the best way to get that water back is to drink up!

    Take it easy. Sometimes if you're out having fun, it's easy to forget to pay attention to your body. But if your body temperature drops even 4 or 5 degrees while you're outside, it can make you feel terrible.____And if you ever feel weak, those are signs that you have to take it easy indoors for a while.

A. Have a snowball fight.

B. Pull a hat onto your head.

C. Well, the truth is that it's good advice for both kinds of weather.

D. Love those clothes.

E. But you have to know how to be safe while you're out having fun.

F. You can stay outside as long as possible to fully enjoy your snow days.

G. That's why you need to be careful with your body's signals.