搜题请搜索小程序“爱下问搜题”
问题 选择题

如图16-6-1所示，质量为m的物体，在跟水平方向成θ角的力F作用下，以速度v匀速前进t秒钟，则物体在这段时间内受到力F的冲量与合外力的冲量分别为（　　）

图16-6-1

A．Ft　Ftcosθ

B．FtsInθ　Ftcosθ

C．Ft　FtsInθ

D．Ft　0

答案

答案：D

力F的冲量就是F与作用时间的乘积IF=Ft.物体以速度v匀速前进，所受合外力为零，合外力对物体的冲量就是零.

阅读理解

Life in the future will be different from life today.But what will the changes be? The population(人口) is growing fast . There will be many people in the world and most of them will live to over 100 years old .

Computer will be very small and useful,and  there will be computers in every home .Travelling will be  very cheap and easy.

And many people will go to other countries for holidays. There will be changes in our food ,too. There will not be much room for cows and sheep, so meat will be very expensive .Maybe  no one will eat it every day .They will eat many fruits and vegetables .Maybe people will be quite  healthy . Work in the future will be different, too. Robots will do hard work .So many people will not have enough work to do.

根据短文内容，判断句子正（T）误 （F）

小题1:All the people in the world will have long life in the future.         

小题2:Life in the future  won’t  be the same as life today.  

小题3:Travelling is very cheap and easy today.  

小题4:People will be healthy because they eat fruits.  

小题5:All the people will not work.  
查看答案
选择题

If I     __  you, I          "hi" to her.    [ ]

A. am, will stay    

B.was; would say  

C. were, will say    

D.were, would say
查看答案