3月11日的日本大地震使福岛第一核电站受损，泄漏放射性物质131I、132I、和134Cs、137Cs等导致核污染。服用一定剂量的碘片可防放射性碘的伤害。被污染的水用硅酸钠来处理。下列说法错误的是
| A．131I、132I、134Cs、137Cs是四种不同的核素 | ||
| B．食用碘盐不能防辐射
| C．碘片的主要成分是I2
| D．用硅酸钠溶液处理污染水，主要利用该溶液具有的粘合性 |
答案：C
| If you left your book on the table overnight, you would find the following morning that it was still exactly where you had left it, provided nobody had moved it. If a ball is made to roll on a very smooth surface, it will roll a long distance unless something stops it or changes its direction. This tendency of an object to remain at rest unless something moves it and to continue moving unless something stops it is known as the Law of Inertia. The following examples show the truth of this law. (a) Put a table-cloth on a table and arrange a pile of books on it. Hold one edge of the table-cloth and pull it quickly. The table-cloth will come off, leaving the pile of books undisturbed. (b) Place a small piece of cardboard on an open jar and place a coin on it directly over its mouth. Use one finger to flick the piece of cardboard away. You will notice that the coin drops into the jar. (c) Sitting in a car which starts suddenly, you feel you are jerked backwards. In fact, you are not jerked backwards. Your lower half, which is in contact with the cushion, is forced to move forward with the car, and the upper part of your body, which remained at rest, is left behind. |
Which of the following is an example of inertia
A．A boat can stay on water.
B．A plane can fly in the air.
C．You can walk faster on a very smooth surface.
D．You can go forward and backward on a swing.