/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 39 The period of a pendulum varies ... [FREE SOLUTION] | 91Ó°ÊÓ

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The period of a pendulum varies directly as the square root of the length of the pendulum and inversely as the square root of the acceleration due to gravity. Find the period when the length is \(121 \mathrm{cm}\) and the acceleration due to gravity is \(980 \mathrm{cm}\) per second squared, if the period is \(6 \pi\) seconds when the length is \(289 \mathrm{cm}\) and the acceleration due to gravity is \(980 \mathrm{cm}\) per second squared.

Short Answer

Expert verified
The period is approximately 3.88468\pi seconds.

Step by step solution

01

Understand the relationship

The period of a pendulum (T) is given by the relationship: \[ T = k \frac{\sqrt{L}}{\sqrt{g}} \] where L is the length of the pendulum, g is the acceleration due to gravity, and k is a constant.
02

Determine the constant (k)

Use the given information to find the value of the constant k. We know that when L = 289 cm and g = 980 cm/s², T = 6\pi seconds. Substitute these values into the formula: \[ 6\pi = k \frac{\sqrt{289}}{\sqrt{980}} \] Simplify and solve for k: \[ 6\pi = k \frac{17}{\sqrt{980}} \] \[ k = 6\pi \cdot \frac{\sqrt{980}}{17} \]
03

Simplify the constant (k)

Simplify the expression for k: \[ k = 6\pi \cdot \frac{\sqrt{980}}{17} \approx 6\pi \cdot \frac{31.304951}{17} \approx 6\pi \cdot 1.8411735 \approx 6 \cdot 1.8411735 \pi \approx 11.047041\pi \]
04

Use the constant to find the new period (T)

Now, use the constant k to find the period when L = 121 cm and g = 980 cm/s². Substitute these values into the formula: \[ T = 11.047041\pi \cdot \frac{\sqrt{121}}{\sqrt{980}} \] Simplify and solve for T: \[ T = 11.047041\pi \cdot \frac{11}{\sqrt{980}} \] \[ T = 11.047041\pi \cdot \frac{11}{31.304951} \] \[ T = 11.047041\pi \cdot 0.3518800507 \approx 3.88468\pi \]

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Key Concepts

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

Direct Variation
In mathematics, direct variation describes a linear relationship between two variables where one variable is a constant multiple of the other. For the period of a pendulum, it varies directly as the square root of its length. This means if the length increases, the period of the pendulum also increases proportionally to the square root of the length.
In our example, if we denote the constant of proportionality by k, we can express the direct variation between the period (T) and the length (L) as: \[T \propto \sqrt{L}\] Here, \[\sqrt{L}\] represents the square root of the length of the pendulum. Understanding this relationship helps in calculating how changes in the length will affect the period.
Inverse Variation
Inverse variation is another key concept in understanding pendulums. It involves a relationship between two variables where one variable increases as the other decreases. The period of a pendulum varies inversely as the square root of the acceleration due to gravity (g). This relationship can be written as: \[T \propto \frac{1}{\sqrt{g}} \] This mathematical expression means that when the acceleration due to gravity increases, the period of the pendulum decreases proportionally, and vice versa. In simpler terms, if gravity is stronger (larger g), the pendulum will swing faster (shorter T). Combining this with direct variation, we get the complete formula: \[T = k \frac{\sqrt{L}}{\sqrt{g}}\]
Physics Formulas
Physics often uses formulas to describe relationships between different physical quantities. The formula for the period of a pendulum incorporates both direct and inverse variation to show a comprehensive relationship: \[T = k \frac{\sqrt{L}}{\sqrt{g}} \] Here’s a quick breakdown of how this works in our example:
  • Calculate the constant (k) using known values: \[6\pi = k \frac{17}{\sqrt{980}} \]. Solve for k to find k = \[11.047041\pi\].
  • Use the value of k to find the period for different lengths and gravitational accelerations. For L = 121 cm and g = 980 cm/s²:

Substitute these values into the formula: \[T = 11.047041\pi \frac{\sqrt{121}}{\sqrt{980}} \]
Simplify to find the period T: \[T \approx 3.88468\pi \]. Understanding and applying these formulas can help solve various physics problems efficiently.

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