Force to lift piston in tube under water · CAP 2006 #22
Physics · fluid-mechanics
Problem
A long vertical tube with a weightless movable piston inside has its lower end under water. The tube is motionless throughout the experiment. The cross-sectional area of the piston is A. The initial position of the piston is just over the surface of the water. Then it is slowly moved upwards. Sketch a graph of the force necessary to lift the piston as a function of the height of the piston.