If you pluck a guitar string hard the sound waves it gives off will have amplitudes.

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Explanation: If you plucked a guitar string lightly, the string would vibrate and give off sound waves with small amplitudes. The resulting sound would be soft, with a low decibel level. If you then plucked the guitar string as hard as you could, the string would vibrate strongly and give off sound waves with large amplitudes. The resulting sound would be loud, with a higher decibel level.  

< > according to newton's third law of motion, forces always act in equal but opposite pairs. another way of saying this is for every action, there is an equal but opposite reaction.< >