论文部分内容阅读
九年义务教育初二物理第一册中有这样一道题:密度计(图1)是测定液体密度的仪器,它是个密封的玻璃管,下端装有铅粒,上端有刻度,把它放在待测的液体中时,它浮在液面上,液面所对的刻度值就是待测液体的密度值.说明为 什么它的刻度值越靠下越大.解析 密度计本身受到的重力是一定的,不论它在哪种液体里漂浮,浮力都等于它受到.的重力.把它放在密度较大的液体中,由于受到的浮力等于重力,排开的液体体积就较小,所以密度计浸入液面下的深度就小.把它放在密度较小的液体中,浸人液面下的深度就较大,所以密度计上的刻度值越靠下越大.
In the second year of compulsory education in the second year of compulsory education, there was such a question in the first volume: the density meter (Fig. 1) is an instrument for measuring the density of liquid. It is a sealed glass tube with a lead pellet at the lower end and a scale on the upper end. When it is in the liquid to be measured, it floats on the liquid surface, and the scale value of the liquid surface is the density value of the liquid to be measured. Explains why the scale value of the liquid is higher downwards. The analytical gravity meter itself receives a certain amount of gravity. No matter which liquid it floats in, the buoyancy is equal to the gravity it receives. Place it in a dense liquid. Since the buoyancy force is equal to gravity, the volume of the liquid to be discharged is small, so the density meter is immersed. The depth below the liquid surface is small. Put it in a liquid with a lower density, the depth of the liquid immersed in the liquid surface is larger, so the scale value on the densitometer is larger down.