两物体平放在水平面上，它们所受重力之比是l：3，与桌面接触面积

搜题请搜索小程序“爱下问搜题”

问题选择题

两物体平放在水平面上，它们所受重力之比是l：3，与桌面接触面积之比是2：1，则桌面受到压强之比分别是（　　）

A．2：3

B．3：2

C．l：6

D．6：1

答案

压力F=G，所以F₁：F₂=G₁：G₂=1：3；

与桌面接触面积之比是2：1，即受力面积之比S₁：S₂=2：1；

∴桌面所受压强之比

=1：6．

故选C．

完形填空

完形填空。

     Years ago, a farmer owned some land along the Atlantic coast. He often advertised for assistants, but he
got no reply as most people feared the terrible storms across the Atlantic coast.
     Finally, a short, thin man came to the farmer. "Well, I can sleep when the wind     1   ," said the little man.
     Although puzzled by this answer, the farmer, badly in need of help, hired him. The little man worked
well around the farm and the farmer felt    2   with the man's work.
     Then one night the wind blew loudly in from the shore. Jumping out of bed, the farmer caught a
lantern (提灯) and    3   next door to the little man. He shook the little man and shouted, "Get up! A storm
is coming! Tie things down    4   they are blown away!"
     The little man rolled over in bed and said firmly, "No, Sir. I told you, I can sleep when the wind blows."
The farmer was very    5   and hurried outside to prepare for the storm himself.    6   , he discovered
everything was tied down.
     The farmer then    7   what his hired man had said. When you're prepared, you have    8   to fear.
Can you sleep when the wind blows through your life?

( )1. A. blows
( )2. A. excited
( )3. A. broke
( )4. A. before
( )5. A. upset
( )6. A. To his surprise
( )7. A. explained
( )8. A. something

B. flies
B. satisfied
B. rushed
B. after
B. angry
B. To his sorrow
B. remembered
B. nobody

C. flows
C. amazed
C. fled
C. as
C. calm
C. To his joy
C. added
C. nothing

D. moves
D. worried
D. knocked
D. when
D. confident
D. To his disappointment
D. understood
D. anything

查看答案

填空题

实验室测量质量的常用工具是____________。把质量为10kg的金属块从地球带到月球上，金属块的质量____________（选填“变大”、“变小”或“不变”），使用天平时，应先将天平放在_________桌面上，然后调节平衡螺母，使横梁平衡。在调节天平横梁平衡的过程中，如果发现指针偏向分度盘的左边，则应将平衡螺母向________（选填“左”或“右”）旋动，在测量的过程中如果同样发现指针偏向分度盘的左边，应。

查看答案