题目

如图所示，空间存在着场强为E＝2.5×102 N/C、方向竖直向上的匀强电场，在电场内一长为L＝0.5 m的绝缘细线，一端固定在O点，另一端拴着质量为m＝0.5 kg、电荷量为q＝4×10－2C的小球．现将细线拉直到水平位置，使小球由静止释放，当小球运动到最高点时细线受到的拉力恰好达到它能承受的最大值而断裂．取g＝10 m/s2.求：   (1)细线能承受的最大拉力； (2)当细线断裂后，小球继续运动到与O点水平方向距离为L时，小球距O点的高度．Read the passage and fill in the blanks with the proper words. Now people know quite a lot about the moon. It is s________ than the stars. There is no air or w______ on the moon, so there aren't any trees or a_____ on it. The moon g________ its light from the sun. The d_______ on the moon get hotter than boiling water. The nights get c________ than the North Pole.