如果

在真空中有两个小球,相距10厘米,A球带+12×10-8库仑的电量,B球带+3×10-8库仑的电量.  (1)现引进第三个小球C,C应放在什么位置,才会处于平衡状态?C球带什么电?带电量是多少?  (2)如果要使A、B、C三个小球都处于平衡状态,C球应放在什么位置?C球带什么电?带电量是多少?

在真空中有两个小球,相距10厘米,A球带+12×10-8库仑的电量,B球带+3×10-8库仑的电量.  (1)现引进第三个小球C,C应放在什么位置,才会处于平衡状态?C球带什么电?带电量是多少?  (2)如果要使A、B、C三个小球都处于平衡状态,C球应放在什么位置?C球带什么电?带电量是多少?

一个质量为50千克的木箱静止在地面上,木箱与地面之间的动摩擦因数为0.2,现在用200牛顿的力拉木箱,如果拉力与水平方向成37°角向上,求木箱的加速度和2秒末的速度.(取,g=10米/秒2)

一个质量为50千克的木箱静止在地面上,木箱与地面之间的动摩擦因数为0.2,现在用200牛顿的力拉木箱,如果拉力与水平方向成37°角向上,求木箱的加速度和2秒末的速度.(取,g=10米/秒2)

Practice 11  (1) Research has also been done into the way people’s behavior changes in a number of small, apparently unimportant ways when they lie. (2) It has been found that if they are sitting down at the same time, they tend to move about in their cha

Practice 11  (1) Research has also been done into the way people’s behavior changes in a number of small, apparently unimportant ways when they lie. (2) It has been found that if they are sitting down