问题
填空题
如图所示，悬挂球质量为1千克，细绳与竖直方向夹角为300，墙壁光滑，则细绳的拉力为______，墙壁对小球的弹力为______牛．
答案
小球的受力如图所示．
根据平衡条件可知，
绳子对圆球的拉力大小T=
=G cos30°
N．20 3 3
N=mgtan30°=
N．10 3 3
故答案为：
N，20 3 3
N．10 3 3
搜题请搜索小程序“爱下问搜题”
如图所示，悬挂球质量为1千克，细绳与竖直方向夹角为300，墙壁光滑，则细绳的拉力为______，墙壁对小球的弹力为______牛．
小球的受力如图所示．
根据平衡条件可知，
绳子对圆球的拉力大小T=
=G cos30°
N．20 3 3
N=mgtan30°=
N．10 3 3
故答案为：
N，20 3 3
N．10 3 3
| 阅读理解。 |
| Here is a new picture. In the picture there are four boys and three girls in a room. They are all students. The boy at the desk is Jim. The girl near the window is Kate. Jim's sister Jane is on the chair. Ann is behind Mike. Mike is at the door. Mike's brother Sam is under the table. Where is Tom? Oh, he is over there, behind the door! They are all very happy. |
| 1. How many students are there in the picture? |
[ ] |
| A. Seven B. Four C. Three D. Five |
| 2. What are the girls' names? |
[ ] |
| A. Jim, Kate and Jane. B. Kate, Ann and Mike. C. Mike, Sam and Tom. D. Kate, Jane and Ann. |
| 3. Where are Ann and Mike? |
[ ] |
| A. On the chair. B. Near the window. C. Under the table. D. At the door. |
| 4. Who is Jane's brother? |
[ ] |
| A. Tom B. Jim C. Mike D. Sam |
| 5. Who is behind the door? |
[ ] |
| A. Mike B. Jim C. Sam D. Tom |