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Home Concept Builders Vibrations and Waves Frequency and Period Help Help 2

Frequency and Period - Questions 2 Help

Vibrating objects undergo back-and-forth vibrations about a fixed location. Two physical quantities that describe these vibrations are frequency and period. While related, they have quite different definitions, meanings, and mathematics.

There is only one question in this Question Group. But the statements are scrambled every time it is presented.
 

Version 1:

Identify the two truths and the one lie from among the following statements:
A vibrating object with a high frequency would be described as having a low period.
A vibrating object with a high frequency is an object that moves a large distance in a short amount of time.
A vibrating object with a high frequency is an object that undergoes a relatively large number of vibrations in a short period of time.

The frequency of a vibrating object refers to how often the object undergoes a complete back and forth cycle about its customary resting position. To calculate such a quantity, one would need to count the number of complete vibrational cycles in a given amount of time and divide the number of cycles by the amount of time. As such, the unit of frequency is cycles per second. This is sometimes equated with the unit Hertz and abbreviated as Hz.

The period of a vibrating object refers to the amount of time it takes the object to complete one cycle. Because it is a time, it is expressed in units such as seconds or minutes. To determine the period, similar measurements can be made as discussed in the previous paragraph - the number of complete vibrational cycles in a given amount of time. The calculation of period from such data involves dividing the time by the number of cycles. As you can see, the unit would be a time unit per cycles or simply the time unit. You might also note that the two quantities period and frequency are reciprocals of each other. As with all reciprocal-related quantities, as the period increases, the frequency would decrease.

Avoiding Misconceptions
It is important to recognize that frequency is not speed. The speed of an object refers to a distance traveled in a given amount of time. An object doesn't even need to "travel" to have a frequency. Frequency simply refers to how often an object vibrates back-and-forth about its fixed position. Words like fast and slow are used to describe an object's speed. But words like very often or not so often are better descriptors of an object's frequency.

Try this link to The Physics Classroom Tutorial for more help with the concepts of frequency and period:

Frequency and Period

Concept Builder Teacher Notes Directions