When a weight is tied on the end of a string and is pulled back and released, it creates a pendulum. The time it takes for the pendulum to swing out and return to its original position is called the period, and depends on the length of the string.

For small release angles, we can use the equation [tex]T = 2 \pi \sqrt{\frac{L}{g}}[/tex], where:
- [tex]T[/tex] is the period of the swing, in seconds.
- [tex]L[/tex] is the length of the string, in meters.
- [tex]g[/tex] is gravity, about [tex]9.8 \, m/s^2[/tex].

If the period is estimated to be 1.36 seconds, determine the length of the string, in meters, to at least 3 decimal places.



Answer :

To determine the length of the string in the pendulum system, given the period (T) of 1.36 seconds, we use the formula for the period of a simple pendulum:

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

Here:
- [tex]\( T \)[/tex] is the period
- [tex]\( \pi \)[/tex] is a constant approximately equal to 3.14159
- [tex]\( L \)[/tex] is the length of the string
- [tex]\( g \)[/tex] is the acceleration due to gravity, which is approximately [tex]\( 9.8 \, \text{m/s}^2 \)[/tex]

We are given [tex]\( T = 1.36 \, \text{s} \)[/tex] and [tex]\( g = 9.8 \, \text{m/s}^2 \)[/tex], and we need to solve for [tex]\( L \)[/tex].

First, let's isolate [tex]\( L \)[/tex] in the equation.

Start by dividing both sides of the equation by [tex]\( 2\pi \)[/tex]:

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

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

Next, square both sides to eliminate the square root:

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

Then, multiply both sides by [tex]\( g \)[/tex]:

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

Now, plug in the values [tex]\( T = 1.36 \, \text{s} \)[/tex] and [tex]\( g = 9.8 \, \text{m/s}^2 \)[/tex]:

[tex]\[ L = 9.8 \left( \frac{1.36}{2 \pi} \right)^2 \][/tex]

Calculate the value inside the parentheses first:

[tex]\[ \frac{1.36}{2 \pi} \approx \frac{1.36}{6.28318} \approx 0.216 \][/tex]

Next, square this result:

[tex]\[ (0.216)^2 \approx 0.0466 \][/tex]

Finally, multiply by [tex]\( 9.8 \)[/tex]:

[tex]\[ L = 9.8 \times 0.0466 \approx 0.459 \][/tex]

Therefore, the length of the string is approximately [tex]\( 0.459 \)[/tex] meters, to three decimal places.