Why does a tuning fork always ring at the same pitch?
Show answer & explanation
Answer: Its prongs' size, shape and metal set one natural note
Room temperature fixes its vibration speed — Temperature barely matters; warming a fork shifts its pitch by only a tiny fraction, and it doesn't lock anything in place. The note is set by the prongs' length, thickness and metal.
Its prongs' size, shape and metal set one natural note ✓ — Every object vibrates most easily at natural frequencies set by its size, shape and material. A tuning fork's prongs are designed so one frequency dominates, and its higher overtones die away within moments, leaving a nearly pure tone.
Its handle filters out every other note — The handle doesn't filter sound; it's a stem to hold, placed where the fork barely vibrates so your hand doesn't damp the prongs. The pitch comes from the prongs themselves.