Physical problem: In the experiment of Madeborg Hemisphere, if the radius of two hemispherical containers is R and the atmospheric pressure is P, why is the force separating the two hemispheres π r&; s Because the ball is symmetrical, so take out half a cross section to analyze. Atmospheric pressure acts evenly on the spherical surface, and the force points to the center of the sphere. After cross coordinate decomposition, the forces in the same direction as the radius are all offset, leaving only the forces acting vertically in the radius direction, namely

F=P S=πR？ P, according to the action and reaction, it only takes πR to separate them? Class p force.