as matter vibrates harder / faster , the volume of the sound produced will increase & a string is a kind of object made from matter ->  as a string vibrates harder / faster , the volume of the sound produced will increase  as a string vibrates harder / faster , the volume of the sound produced will increase & as a string of a musical instrument is plucked harder , the string will vibrate harder / faster ->  as a string of a musical instrument is plucked harder, the volume of the sound will increase  as a string of a musical instrument is plucked harder, the volume of the sound will increase & as a string of a musical instrument is plucked harder , the pitch produced will not change ->  as the string of a musical instrument is plucked harder, the pitch will stay the same and the volume of the sound will increase  as the string of a musical instrument is plucked harder, the pitch will stay the same and the volume of the sound will increase & a guitar is a kind of musical instrument -> as the string of a guitar is plucked harder, the pitch will stay the same and the volume of the sound will increase