从高中物理 (乙种本 )上册第八章练习三开始 ,以后多种版本的中学物理课本都有这样一道练习题 :图 1把一块洗净的玻璃板吊在橡皮筋的下端 ,使玻璃板水平地接触水面 (如图 1 ) ,如果你想使玻璃板离开水面 ,用手向上拉橡皮筋 ,拉动玻璃的力是否大于玻璃板受的重力 ?动手试一试 , From the high school physics (second edition) booklet Chapter 8 Exercise 3, afterwards, a variety of versions of the middle school physics textbooks have such an exercise: Figure 1 A clean glass plate hanging from the bottom of the rubber band, the glass plate Touch the water surface horizontally (see Figure 1). If you want to move the glass out of the water and pull the rubber band upwards by hand, is the glass pulling force greater than the glass plate? Try it out.