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一液体只能从高压流向低压吗? “电流从高电位向低电位流向,就象液体从高压向低压流动一样.”这种比喻很可能给学生建立一个错误的观点,即液体只能从高压向低压流动,就好像电流只能从高电位向低电位流向一样.事实上,液体是可以从低压向高压流动的.当液体流经水平放置的管径增大的管道(流速u减小),根据伯努利方程(p+pgz+pu~2/2=h),对于理想液体,h量应守恒,所以此过程压强p是增大的.对于实际液体同样能从低压流向高压,当通过一输送管道把高处(山顶)液体向低处(山脚)输送时,山顶处压强始终是低于山脚处压强的.
Can a liquid only flow from a high pressure to a low pressure? “The current flows from a high potential to a low potential, just as the fluid flows from a high pressure to a low pressure.” This metaphor is likely to give students a false point of view that liquid can only be from high pressure Flow to low pressure as if the current can only flow from high potential to low potential. In fact, the liquid can flow from low pressure to high pressure. When the liquid flows through horizontally placed pipe with increased diameter (flow u decreases) According to Bernoulli’s equation (p + pgz + pu ~ 2/2 = h), for an ideal liquid, the amount of h should be conserved, so the pressure p is increased during this process. For the actual liquid, it can also flow from low pressure to high pressure. When a high point (mountain top) liquid is conveyed to a low place (mountain foot) through a conveying pipe, the pressure at the top of the mountain is always lower than the pressure at the foot of the mountain.