1- The correct answer is A. For resonance to occur, the object must experience a frequency equal to its natural frequency.
The resonance is a phenomenon that occurs when a body capable of vibrating is subjected to the action of a periodic force, whose vibration period approaches the characteristic period of vibration of said body.
2- The correct answer is A. When tightening a string on a guitar, its natural frequency increases.
3- The correct answer is D. Resonance in air columns is used in trumpets.
A trumpet exhibits natural resonance frequencies, which follow a harmonic sequence, quite close to the tenth harmonic.
4- The correct answer is D. The term that describes the number of crests that pass a point in a given amount of time is frequency.
Frequency is a quantity that measures the number of repetitions per unit of time of any phenomenon or periodic event.
5- The correct answer is C. A human could detect a sound frequency of 50 hertz, as the human ear has a limited range of perception, which very roughly (since it varies in each individual and with age for only one) ranges from 20 Hz to 20,000 Hz.
