质量为选m的物体，由静止开始下落,空气阻力为 15mg ，在物体下落h的过程中，下列说法正确的是 ( )_刷题宝

题干

质量为选m的物体，由静止开始下落,空气阻力为

1

5

mg ，在物体下落h的过程中，下列说法正确的是 ( )

A：物体重力做的功为mgh

B：物体的动能减少了mgh

C：物体重力势能增加了mgh

D：物体克服阻力所做的功为 $\frac{1}{5} m g h$

上一题下一题 0.0难度选择题更新时间:2019-04-22 02:41:56

答案(点此获取答案解析）

A,D

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如图所示，容器内的水中有一个被细线系着的正方体木块，此时容器内的水深为0.2m，木块的边长为0.05m，木块的密度为0.6×10³kg/m³．试求：

同类题2

不能用于区别稀硫酸和氢氧化钠溶液的是（）

同类题3

下列物质中，在核糖体上合成的是
①性激素 ②抗体 ③淀粉 ④唾液淀粉酶 ⑤纤维素 ⑥胰岛素

同类题4

根据短文内容，选择正确答案。
E
  Many parents today worry about their children's diets. Then what is a healthy diet for children? Miss Jones from Happy Children Hospital gives the following advice:
   ◆Children shouldn't eat food with too much salt, because it can cause high blood pressure(高血压).
    ◆Children should eat food with less fat, oil and sugar. They should not eat too much junk food.
    ◆Fruit and vegetables are rich in vitamins(维生素). Children need to eat fruit and vegetables often.
   ◆Water is important to everyone. Children need to drink enough water every day.
  ◆Children need to eat breakfast every day. It is good for their bodies and minds.

同类题5

下列说法中不正确的是（）

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