问题 问答题

气球以v0=10m/s的速度匀速竖直上升的过程中,一个小铁球从气球上掉下并且在6s末到达地面.求铁球刚刚脱离气球时的高度(g取10m/s2,铁球下落过程中不计空气阻力)

答案

设小球刚刚离开气球时距地面的高度为H,

取初速度的方向为正方向,

则有:H=v0t-

1
2
gt2

代入数据得:H=-120m

答:则此时小球离地面的高度120 m.

单项选择题

Randy Kraus was paralyzed. His left side was useless. But his right hand was (1) enough to lift a bucket to his forehead. Once, he’d been a police officer and owned a private-eye agency. Once, he’d been p and able. Now, he felt he was nothing.

His (2) started with Parkinson’s disease, but it didn’t (3) there. In July 2002, the 60 year old Kraus went into the hospital for an operation to control the shaking. (4) , during the operation, he had a stroke. He was paralyzed. The (5) man, who loved golf, could think, but couldn’t (6) . Kraus wanted the doctors to (7) it to him straight. "You may never walk again, " they told him. "Maybe you won’t (8) be able to talk. "

Once at home, he (9) he couldn’t lift a fork or take a drink by himself. Physical treatment was so painful and slow. What did he have to (10) for So now Kraus held the gun against his head. (11) the cold metal on his skin, he began to consider not his pain, but the pain he (12) cause his wife, daughters and grandchildren. He didn’t pull the trigger.

"You are where you are", his exercise physiologist, Andrew Garud told him. "The pace would be slow; the pain would be (13) . But as long as you are (14) , you have the ability to get better. " After three months of (15) with Garud, Kraus wanted to see if he could (16) . He could. Then he took three steps, sat down and cried like a baby. One step (17) to another. Next he managed a short walk. It was the hardest (18) of Kraus’s life.

Garud kept saying he could (19) more. Now, Kraus can brush his teeth, shave himself and get around the house with a walker. Little success only the paralyzed can (20) understand.

14().

A.awake

B.alive

C.aware

D.available

单项选择题