What music would you like to make?
3
Amplitude of vibrations
The amplitude of the vibration of a vibrating object governs how loud the sound is. If you tap a drum very gently you get a quiet sound of a particular frequency. If you bang the same drum hard you get a sound of the same frequency but much louder. The energy in the vibrating object is proportional to the square of the amplitude. If you hit the drum twice as hard you put four times as much energy into the skin; if you hit the drum three times as hard you put nine times as much energy into the skin.
The same principle applies to the piano. If you hit the key hard you get a much louder note than with a gentle tap. As soon as you lift your finger off the key a damper bar touches the string preventing it from vibrating so the sound stops. You can press the sustain pedal which stops the damper bar working and the string continues to vibrate until all the energy has been dissipated.
The loudness of the sound will decrease (i.e. get quieter and quieter) as the amplitude of the vibration decreases.