题目

在船与河岸距离相行的条件下，为什么人从小船跳上岸比人从大船跳上岸要难些（水的阻力不计）？1mol葡萄糖（C6H12O6）在人体内氧化产生2870kJ能量，其中1250kJ转化为ATP供人体运动需要，其余为人体供热。某人质量为m=60kg，以v1=5m/s的速度从质量为M=100kg的船上跳上岸，至少需要消耗多少质量的葡萄糖？ 答案：解：设人从船上跳上岸时，船获得的反冲速度为v2，由由动量守恒定律得 mv1=Mv2，得v2=3m/s。 （3分）人跳上岸的过程中，对人和船所做的功 W=mv12/2 + Mv22/2=1200J。（3分）即葡萄糖在人体内氧化产生的能量中，需要12kJ转化为ATP供人体运动需要。葡萄糖的摩尔质量为180g/mol，则消耗的葡萄糖的质量为 △m=1.2×180Due to the increasing number of violence acts produced in schools all over the world, more and more parents prefer to have their children educated at home rather than at school. This way they can assure their safety and well-being. Teachers and school representatives are trying to improve the situation in schools by increasing the number of the persons in charge of the safety of the students. The main reason for violence acts are the films and cartoons that fill the children’s time. They want to do everything they watch on TV and never think of the consequences, they may hurt a classmate or a teacher. On the other hand, parents are not fully satisfied with the children’s results obtained in classes and they consider private classes would have better results. When a teacher is obliged to watch 30 students in class he can’t probably see what each of them is doing, how he is writing, or if he understood the explanations. At home the teacher can explain in details everything the child doesn’t understand as many times as he considers proper. Many times, the child grows fond of the teacher at home, who becomes his best friend, and who helps him whenever he needs someone to talk to. However, the best solution would be a mixture between the education received at school and that at home. School makes children communicate and socialize. Keeping a child at home for fear something bad might happen to him, only makes the child’s character weak and prevents him from knowing what real life is. Staying in a crystal ball only does harm to the child. All in all, schools have been created to help children, not to harm them, so it’s best to keep children in these special places, where they learn, laugh, have fun and make new friends.1. The writer’s purpose in writing the text is to_____________ .A. teach parents the ways to keep the children safeB. show solutions to developing children’s characterC. explain the main reason for violence acts in schoolsD. analyze an education problem and give opinions2. Which of the following might be the best title of the passage?A. Advantages and Disadvantages of Private ClassesB. Who is to Blame, Parents or Schools?   C. which is Better, School Study or Home Study?  D. The Relationship between Teachers and Children   3. What does “a crystal ball” in the passage refer to?A. A toy that can be used for entertainment.B. A safe and comfortable environment.C. An object that is made of crystal.D. A setback that is hard to overcome.4. We call infer from the passage that____________.A. violence TV programs have bad effects on children’s behaviorB. the teacher at home is more patient than the teacher at schoolC. children today are weak from lack of sense of right and wrongD. there are too many students in class for a teacher to teach