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The formula [tex]T = 2 \pi \sqrt{\frac{L}{32}}[/tex] relates the time, [tex]T[/tex], in seconds for a pendulum with the length, [tex]L[/tex], in feet, to make one full swing back and forth.

What is the length of a pendulum that makes one full swing in 2.2 seconds? Use 3.14 for [tex]\pi[/tex].

A. 2 feet
B. 4 feet
C. 11 feet
D. 19 feet



Answer :

To solve for the length \( L \) of a pendulum that makes one full swing in 2.2 seconds using the given formula \( T = 2 \pi \sqrt{\frac{L}{32}} \), we need to follow these steps:

1. Substitute the given values into the formula \( T = 2 \pi \sqrt{\frac{L}{32}} \):
[tex]\[ 2.2 = 2 \times 3.14 \times \sqrt{\frac{L}{32}} \][/tex]

2. Isolate the square root term. First, divide both sides by \( 2 \times 3.14 \):
[tex]\[ \frac{2.2}{2 \times 3.14} = \sqrt{\frac{L}{32}} \][/tex]

3. Calculate the value of the left-hand side:
[tex]\[ \frac{2.2}{6.28} \approx 0.35 \][/tex]
Thus,
[tex]\[ 0.35 = \sqrt{\frac{L}{32}} \][/tex]

4. Square both sides to eliminate the square root:
[tex]\[ (0.35)^2 = \frac{L}{32} \][/tex]
[tex]\[ 0.1225 = \frac{L}{32} \][/tex]

5. Isolate \( L \) by multiplying both sides by 32:
[tex]\[ L = 0.1225 \times 32 = 3.92 \][/tex]

The calculated value of \( L \) is approximately 3.92 feet.

Next, we compare this length to the given options (2 feet, 4 feet, 11 feet, 19 feet) to find the closest match:

- Subtract 3.92 from each option:
[tex]\[ |2 - 3.92| = 1.92 \][/tex]
[tex]\[ |4 - 3.92| = 0.08 \][/tex]
[tex]\[ |11 - 3.92| = 7.08 \][/tex]
[tex]\[ |19 - 3.92| = 15.08 \][/tex]

The option 4 feet has the smallest difference from 3.92 feet.

Therefore, the closest length of the pendulum that makes one full swing in 2.2 seconds is:
[tex]\[ \boxed{4 \text{ feet}} \][/tex]

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