问题
填空题
小汽船在静水中的速度为4m/s，河水流速是3m/s，则：当小汽艇垂直于河岸航行时，小汽船的速度为______m/s，船的航行方向与水流方向夹角为______．
答案
当静水速与河岸垂直时，合速度的大小v=
=5m/s．设船的航行方向与水流方向夹角为α，则tanα=v静2+v水2
=v静 v水
．所以α=53°．4 3
故答案为：5，53°
搜题请搜索小程序“爱下问搜题”
小汽船在静水中的速度为4m/s，河水流速是3m/s，则：当小汽艇垂直于河岸航行时，小汽船的速度为______m/s，船的航行方向与水流方向夹角为______．
当静水速与河岸垂直时，合速度的大小v=
=5m/s．设船的航行方向与水流方向夹角为α，则tanα=v静2+v水2
=v静 v水
．所以α=53°．4 3
故答案为：5，53°
Passage Four
According to the passage, which of the following statements is NOT true
A．The potential health hazards of mobile phones call for further research.
B．The Australian scientists find no connection between growth of tumors in human body and radiation from mobile phones.
C．The Italian scientists’ belief is shared by other scientists.
D．The British government inquiry didn’t establish any link between health risks and use of mobile phones.