（1）已知物体静止在水平地面上，物体重G=10N， 另受到一个拉力F=12N的作

（7分）如图甲所示，一个边长为1m的正方体静止在湖底，上表面离水面深度为h．现用一根粗细和重力不计的绳子，将该物体从水底竖直向上拉，直至完全拉出水面，在整个拉动过程中物体始终保持匀速运动，拉力的大小随时间变化的关系如图乙所示．（g=10N/kg，ρ_水=1.0×10³kg/m³）求：

（1）物体在露出水面前受到水的浮力是多少N？

（2）物体在露出水面前受到绳子的拉力是多少N？

（3）物体的密度是多少kg/m³

（4）物体在水底时，上表面受到水的压强是多少Pa？

Robert Owen was born in Wales in 1771. At the age of ten he went to work. His employer had a large private library so Owen was able to educate himself. He read a lot in his spare time and at nineteen he was given the job of superintendent(监工) at a Manchester cotton mill. He was so successful there that he persuaded his employer to buy the New Lanark mill in Scotland.

When he arrived at New Lanark it was a dirty little town with a population of 2,000 people. Nobody paid any attention to the workers' houses or their children's education. The conditions in the factories were very bad. There was a lot of crime and the men spent most of their wages on alcoholic drinks.

Owen improved the houses. He encouraged people to be clean and save money. He opened a shop and sold the workers cheap, well-made goods to help them. He limited the sale of alcoholic drinks. Above all, he fixed his mind on the children's education. In 1816, he opened the first free primary school in Britain.

People came from all over the country to visit Owen's factory. They saw that the workers were healthier and more efficient than in other towns. Their children were better fed and better educated. Owen tried the same experiment in the United States. He bought some land there in 1825,but the community was too far away. He could not keep it under control and lost most of his money.

Owen never stopped fighting for his idea. Above all he believed that people are not born good or bad. He was a practical man and his ideas were practical. "If you give people good working conditions," he thought, "they will work well and, the most important thing of all, if you give them the chance to learn, they will be better people."

小题1:For Owen, his greatest achievement in New Lanark was _____________.

A．improving worker's houses

B．helping people to save money

C．preventing men from getting drunk

D．providing the children with a good education小题2:From the passage we may infer that Owen was born ___________.

A．into a rich family

B．into a noble family

C．into a poor family

D．into a middle class family小题3:Owen's experiment in the United States failed because _______.

A．he lost all his money

B．he did not buy enough land

C．people who visited it were not impressed

D．it was too far away for him to organize it properly小题4:We may infer form the passage that no children in Britain could enjoy free education until ____.

A．1771

B．1816

C．1825

D．1860

木瓜的功效是（）

A.祛风通络，清热泻火

B.祛风通络，强筋骨

C.舒筋通络，化湿和胃

D.祛风湿，利关节，解毒

E.舒筋活络，安胎

The great advance (91) rocket theory 40 years ago showed that liquid-fuel rockets were far (92) in every respect to the skyrocket with its weak solid fuel, the only kind of rocket then known. (93) , during the last decade, large solid-fuel rockets with (94) fuels about as powerful as liquid fuels have (95) their appearance, and it is a favorite layperson’s question to (96) which one is "better". The question is meaningless. (97) might as well ask whether a gasoline or a diesel engine is "better". It all (98) on the purpose. A liquid-fuel rocket is complicated, (99) has the advantage that it can be controlled beautifully. The burning of the rocket engine can be stopped completely; it can be reignited when (100) . (101) , the thrust can be made to vary by adjusting the speed of the fuel pumps. A solid-fuel rocket, on the other hand, is rather (102) in construction, (103) hard to build when a really (104) size is desired. But once you have a solid-fuel rocket, it is ready for action (105) very short notice. A liquid-fuel rocket has to be fueled first and cannot be (106) readiness for very long after it has been fueled. (107) , once a solid-fuel rocket has been ignited, it will keep burning. It cannot be stopped and reignited (108) desired (it could conceivably be stopped and reignited after a pre-calculated time of burning has elapsed, and its thrust cannot be varied. Because a solid-fuel rocket can be kept ready for a long time, most military missiles (109) solid fuels, but human-piloted spaceflight needs the fine adjustments that can (110) be provided by liquid fuels.

A．inferior

B．better

C．worse

D．superior

为什么玻璃的实质强度较理论强度低