Forces inside hadrons: Pressure, surface tension, mechanical radius, and all that

[1 ]Petersburg Nuclear Physics Institute, Gatchina, 188300, St. Petersburg, Russia

[2 ]Institut für Theoretische Physik II, Ruhr-Universität Bochum, D-44780 Bochum, Germany

[3 ]Department of Physics, University of Connecticut, Storrs, CT 06269, USA