Pressure is force over area. So assuming your cube is at rest and on earth, then the force is mass x gravity and the pressure is mass x gravity / area.
A string quartet is made up of four musicians playing two violins, a viola, and a cello. These are all string instruments played either by plucking the strings or using a bow. The violins are the smallest and typically play the higher notes. The viola and cello are larger instruments and play the lower notes.
Size of the ensemble was expanded due to the demands of Beethoven. Improved woodwinds and brass instruments, such as the Boehm key systems on flutes, clarinets, and oboes. New instruments such as the tuba, contrabassoon, English horn, and string bass added depth to the ensemble. String section grew for proper balance.