问题 选择题

如图所示,质量为10kg的物体在水平面上向右运动,此时受到水平向右外力作用F=20N,物体与平面之间的动摩擦因数为0.2,则物体受到的合力是(g=9.8m/s2)(  )

A.20N,水平向右

B.19.6N,水平向左

C.39.6N,水平向右

D.0.4N,水平向右

答案

依题意,物体相对于地面向右运动,受到地面的滑动摩擦力方向向左.物体在水平面上运动,F也在水平方向,则物体对地面的压力大小等于物体的重力,

即FN=mg,所以物体受到的滑动摩擦力大小为f=μFN=μmg=0.2×10×9.8N=19.6N

所以F=F-f=20-19.6N=0.4N,方向水平向右.

故选D

翻译题

阅读理解。

    Pandas are black-and-white Chinese bears. (1)These large pandas have a big head, a heavy body, rounded

ears, and a short tail.

   The Chinese people call the panda "Da Xiong Mao", which means" big bear cat" in Chinese. (2)This bear is

quite different from other bears. It has unusual cat-like eyes. (3)大熊猫的视力非常好.

   The largest pandas grow to be about 115 kg, about the weight of a large adult human. They are about 1.6

to 1.8 m long. Most pandas grow to be about 80cm tall and weigh about 80kg.

    Pandas eat about 18kg of food each day. Bamboo is their favourite. These bamboo plants only grow in a

few places. In zoos, pandas eat bamboo,carrots, apples and sweet potatoes.

    Pandas have 42 teeth. (4) Pandas have very thick fur that keeps them warm in cold weather. Their fur is

waterproof (防水的).

    Pandas only live in a few mountains in central (中心的) and western China, mainly in Sichuan, Shanxi,

and Gansu provinces.

    (5)有大约1000至1500只大熊猫生活在中国. There are about 120 pandas living in zoos in the world.

1. 将 (1) 处英语翻译成中文。

                                                                                                         

2. 将 (2) 处英语翻译成中文。

                                                                                                         

3. 将 (3) 处中文翻译成英语。

                                                                                                         

4. 将 (4) 处英语翻译成中文。 

                                                                                                         

5. 将 (5) 处中文翻译成英语。

                                                                                                         

选择题