The time, in seconds, that it takes a pendulum to swing back and forth is modeled by the equation:
[tex]\[ T = 2 \pi \sqrt{\frac{L}{32}} \][/tex]
where [tex]\( L \)[/tex] is the length of the pendulum in feet.

What is the approximate length of a pendulum that takes [tex]\( 2.4 \pi \)[/tex] seconds to swing back and forth?

A. 1.72 ft
B. 3.05 ft
C. 38.40 ft
D. 46.08 ft



Answer :

To determine the length of a pendulum that takes [tex]\(2.4\pi\)[/tex] seconds to swing back and forth, we will use the formula for the period of a pendulum:

[tex]\[ T = 2\pi \sqrt{\frac{L}{g}} \][/tex]

Where:
- [tex]\( T \)[/tex] is the period (time for one complete cycle).
- [tex]\( L \)[/tex] is the length of the pendulum.
- [tex]\( g \)[/tex] is the acceleration due to gravity, which is approximately [tex]\( 32 \, \text{ft/s}^2 \)[/tex] in this problem.

We are given [tex]\( T = 2.4\pi \)[/tex] seconds. We need to find [tex]\( L \)[/tex].

First, we rearrange the formula to solve for [tex]\( L \)[/tex]:

[tex]\[ T = 2\pi \sqrt{\frac{L}{g}} \][/tex]

Divide both sides by [tex]\( 2\pi \)[/tex]:

[tex]\[ \frac{T}{2\pi} = \sqrt{\frac{L}{g}} \][/tex]

Square both sides to get rid of the square root:

[tex]\[ \left( \frac{T}{2\pi} \right)^2 = \frac{L}{g} \][/tex]

Multiply both sides by [tex]\( g \)[/tex] to isolate [tex]\( L \)[/tex]:

[tex]\[ L = g \left( \frac{T}{2\pi} \right)^2 \][/tex]

Substitute the known values [tex]\( T = 2.4\pi \)[/tex] and [tex]\( g = 32 \)[/tex]:

[tex]\[ L = 32 \left( \frac{2.4\pi}{2\pi} \right)^2 \][/tex]

Simplify the expression inside the parentheses:

[tex]\[ L = 32 \left( \frac{2.4\pi}{2\pi} \right)^2 = 32 \left( \frac{2.4}{2} \right)^2 = 32 \left( 1.2 \right)^2 \][/tex]

Calculate [tex]\( (1.2)^2 \)[/tex]:

[tex]\[ (1.2)^2 = 1.44 \][/tex]

Then multiply by 32:

[tex]\[ L = 32 \cdot 1.44 = 46.08 \][/tex]

Therefore, the approximate length of the pendulum that takes [tex]\( 2.4\pi \)[/tex] seconds to swing back and forth is:

[tex]\[ \boxed{46.08 \, \text{ft}} \][/tex]

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