A weight hangs from a spring and bobs 3 inches above and below an equilibrium position. The weight takes 8 seconds to complete a full cycle (period [tex]$=8$[/tex]). When graphed, time is on the horizontal axis and position relative to equilibrium is on the vertical axis.

Which statements are true? Check all that apply.

A. The amplitude is 6.
B. The graph is stretched vertically by a factor of 3.
C. The frequency is [tex]$\frac{1}{8}$[/tex].
D. The graph is compressed horizontally by a factor of [tex]$\frac{\pi}{4}$[/tex].
E. The frequency is 8.



Answer :

To determine the truthfulness of each statement given the problem, we can go through them one by one, ensuring we understand each concept.

### Statement 1: The amplitude is 6.
- Amplitude is the maximum displacement from the equilibrium position.
- According to the problem, the weight bobs 3 inches above and 3 inches below the equilibrium position.
- Therefore, the amplitude is 3 inches, not 6 inches.
- This statement is false.

### Statement 2: The graph is stretched vertically by a factor of 3.
- Stretching vertically by a factor means that the amplitude of the motion is multiplied by that factor.
- Since the amplitude is given as 3 inches, the vertical stretch factor refers to this amplitude.
- This statement is true.

### Statement 3: The frequency is \( \frac{1}{8} \).
- Frequency is the reciprocal of the period. It represents how many cycles occur per unit of time.
- Given the period \( T = 8 \) seconds, the frequency \( f \) is \( \frac{1}{T} = \frac{1}{8} \) cycles per second (Hz).
- This statement is true.

### Statement 4: The graph is compressed horizontally by a factor of \( \frac{\pi}{4} \).
- Horizontal compression or stretching relates to changes in the period, typically involving phase shifts or frequency multipliers.
- In the given context, there is no indication of a horizontal compression by a factor of \( \frac{\pi}{4} \).
- This statement is false.

### Statement 5: The frequency is 8.
- Again, the frequency \( f \) is the reciprocal of the period \( T = 8 \) seconds, i.e., \( f = \frac{1}{8} \) Hz.
- Therefore, the frequency is not 8 Hz.
- This statement is false.

After checking all the statements based on the information provided in the problem:

- The amplitude is 6. False
- The graph is stretched vertically by a factor of 3. True
- The frequency is \( \frac{1}{8} \). True
- The graph is compressed horizontally by a factor of \( \frac{\pi}{4} \). False
- The frequency is 8. False

The correct assessments match with the following results:
- (False, True, True, False, False)