Questions

Beats means the periodic increase and decrease in loudness heard when two notes of nearly the same frequency are sounded simultaneously.

Turbines are machines powered by rotating blades.

Helioseismology is the study of the solar interior using observations of waves on the Sun's surface. It has done much to improve our understanding of the interior of the Sun, testing the physical inputs used to model stellar interiors and providing a detailed map of the Sun's structure and internal rotation.

Alfred Bernhard Nobel was a Swedish chemist, engineer, inventor, businessman, and philanthropist. Known for inventing Dynamite, Nobel also owned Bofors, which he had redirected from its previous role as primarily an iron and steel producer to a major manufacturer of cannon and other armaments.