功的原理有不同的表述方式,如:表述Ⅰ:利用任何机械,人们所做的功都等于不用机械而直接用手所做的功.表述Ⅱ:使用任何机械都不省功.两种表述中,表述Ⅰ仅适用于理想机械,即不计摩擦,不计机械本身重等因素的情况,而表述Ⅱ则不受此限制.在初中物理竞赛中,有些力学题,如果按常规思路简直无法求解,而利用功的原理往往可以使不少复杂问题获得迅速的求解.例1如图1所示,左右两个圆柱形容器中 The principle of work has different ways of expression, such as: Expression I: With any machine, the work done by people is equal to the work done by hand without the use of machinery. Expression II: The use of any machine does not save power. In the above description, the expression I applies only to the ideal machine, that is, regardless of friction, not counting the weight of the machine itself, while the expression II is not limited by this. In the junior high school physics competition, there are some mechanical problems that cannot be solved simply by conventional thinking. The use of power can often cause many complicated problems to be solved quickly. Example 1 As shown in Figure 1, two cylindrical containers