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A simple pendulum is swinging back and forth through a small angle, its motion repeating every \(1.25 \mathrm{s}\). How much longer should the pendulum be made in order to increase its period by \(0.20 \mathrm{s} ?\)

Short Answer

Expert verified
The pendulum should be lengthened by approximately 0.131 m.

Step by step solution

01

Understand the Pendulum Period Formula

The period of a simple pendulum is given by the formula \( T = 2\pi \sqrt{\frac{L}{g}} \), where \( T \) is the period of the pendulum, \( L \) is the length of the pendulum, and \( g \) is the acceleration due to gravity (approximately \( 9.8 \, \text{m/s}^2 \) on Earth). Our task is to find how much the length \( L \) should be increased to increase the period \( T \) by \( 0.20 \, \text{s} \).
02

Calculate the Original Length

The original period of the pendulum is \( T_1 = 1.25 \, \text{s} \). We need to find the original length \( L_1 \). Rearranging the period formula gives \( L_1 = \frac{gT_1^2}{4\pi^2} \). Substituting \( T_1 = 1.25 \, \text{s} \) and \( g = 9.8 \, \text{m/s}^2 \), we get:\[ L_1 = \frac{9.8 \times (1.25)^2}{4\pi^2} \approx 0.387 \, \text{m}. \]
03

Calculate the New Period

The new period of the pendulum \( T_2 \) is \( T_1 + 0.20 = 1.25 + 0.20 = 1.45 \, \text{s} \).
04

Calculate the New Length

We use the period formula again to find the new length \( L_2 \) corresponding to \( T_2 = 1.45 \, \text{s} \):\[ L_2 = \frac{gT_2^2}{4\pi^2}. \]Substituting \( T_2 = 1.45 \, \text{s} \) gives:\[ L_2 = \frac{9.8 \times (1.45)^2}{4\pi^2} \approx 0.518 \, \text{m}. \]
05

Find the Increase in Length

To find how much longer the pendulum should be made, calculate the difference between the new length \( L_2 \) and the original length \( L_1 \):\[ \Delta L = L_2 - L_1 = 0.518 \, \text{m} - 0.387 \, \text{m} \approx 0.131 \, \text{m}. \]
06

Conclusion

The pendulum should be lengthened by approximately \( 0.131 \, \text{m} \) to increase its period by \( 0.20 \, \text{s} \).

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

simple pendulum formula
In the world of physics, pendulums are a classic example of simple harmonic motion. The formula for calculating the period, which is the time it takes to complete one full swing, is crucial. This "simple pendulum formula" is given by \( T = 2\pi \sqrt{\frac{L}{g}} \). Here:
  • \( T \) represents the period - essentially, how much time the pendulum takes to do a full cycle of swinging back and forth.
  • \( L \) is the length of the pendulum rod or string, measured in meters (\( m \)).
  • \( g \) is the acceleration due to gravity, which is approximately \( 9.8 \text{ m/s}^2 \) on Earth.
If you understand this formula, you can predict how the period changes if you adjust the length of the pendulum. The longer the pendulum, the longer the period. This formula is key to solving any problems involving a simple pendulum.
pendulum length adjustment
When working with pendulums, sometimes you'll want to adjust their periods. This means you'll be changing the pendulum's length. Knowing how to calculate these adjustments is important.To find the original length of the pendulum that has a known period, rearrange the simple pendulum formula addressing \( L = \frac{gT^2}{4\pi^2} \). Start with the known period:
  • Original period \( T_1 = 1.25 \text{ s} \).
  • Calculate its length: \( L_1 = \frac{9.8 \times (1.25)^2}{4\pi^2} \approx 0.387 \text{ m} \).
Now, after deciding to increase the period, you can find the new length:
  • New period \( T_2 = 1.45 \text{ s} \), added \( 0.20 \text{ s} \) to the original period.
  • New length becomes \( L_2 = \frac{9.8 \times (1.45)^2}{4\pi^2} \approx 0.518 \text{ m} \).
If the period changes, the pendulum's length must also change accordingly. This method shows how to make precise adjustments, ensuring your pendulum meets the desired time specifications.
period increase calculation
Sometimes you'll need to adjust a pendulum so it ticks at the right interval. This can be quite practical in timekeeping or scientific experiments. To increase the period by a certain amount, first understand how this affects the pendulum's length.Imagine your goal is to lengthen the period by \( 0.20 \text{ s} \). Now:
  • Determine the initial pendulum period as \( T_1 = 1.25 \text{ s} \) with its length calculated as \( 0.387 \text{ m} \).
  • The new target period \( T_2 = 1.45 \text{ s} \) should be set into the formula to obtain the new length \( L_2 \) as \( 0.518 \text{ m} \).
The final step is to find out how much longer the pendulum should be made by calculating the difference:
  • \( \Delta L = L_2 - L_1 = 0.518 \text{ m} - 0.387 \text{ m} \approx 0.131 \text{ m} \).
This increase in length ensures that the new period is achieved, demonstrating how pendulum behavior can be finely tuned through length variation. Such calculations are important for anyone working with pendulums, whether it's for fun experiments or serious scientific inquiries.

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Most popular questions from this chapter

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