Timbre refers to the perceived sound quality of musical notes and tones. Distinguishes different types of sound production and instruments. Even identical instruments can sound different despite same pitch and volume
Shows red in acidic medium and yellow in basic medium. Changes from red to orange to yellow in decreasing acidity. Has pKa of 3.47 in water at 25°C. Absorbs UV-vis spectrum between 350-550 nm, peak at 464 nm
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Primary standards are pure, easily weighed reagents representing substance moles. Used in titration to determine unknown concentrations. Must be high purity, stable, and hygroscopic. Common examples include NaCl for AgNO3 and KHP for perchloric acid
Crandall and Mark systematized knowledge in random vibrations theory. Digital computers enabled analysis of complex systems in 1950s. Finite element method developed for aircraft structures
Natural frequency is the vibration frequency of an object without external forces. Simple objects have single natural frequency, complex ones have multiple. Natural frequency determines sound production, resonant frequency is similar but with periodic force