Question

physics any two musical instruments

Answer 1

you can write whatever you wish - flute, drum, piano, guitar

Answer 2

Sound note is produced in percussion instrument like drum , tabla , bongo,dhol etc is by striking or beating the surface which cause vibration of the surface which in turn produces the sound.
String based instrument like guitar produces it's sound by vibrating their string.
The pitch in string instrument depend on the thickness of the string, so guitar or other string based instrument have different thickness strings.