题目

综合填空    Hello, I'm Mike. I'm from America. I'm amiddle school s like you. I have a computer. I use it every day. Becausewe do our homework on our c Do you know how we write our homework onthe computer? It's very easy. F use the mouse, c new document" and o a new document.N , you write your homework in the new document. U thekeyboard, you click "s " and write a name for it in thebox. T click "save" again. F , click "print"and "OK".一质量为m、带电荷量为+q的小球从距地面高h处以一定初速度水平抛出．在距抛出点水平距离L处，有一根管口比小球直径略大的竖直细管．管上口距地面h/2.为使小球能无碰撞地通过管子，可在管子上方的整个区域加一个场强方向水平向左的匀强电场，如图13-12-15所示，求： 图13-12-15（1）小球初速v0；（2）电场强度E的大小；（3）小球落地时动能Ek．