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Two ropes in a vertical plane exert equal-magnitude forces on a hanging weight but pull with an angle of \(86.0^{\circ}\) between them. What pull does each one exert if their resultant pull is 372 \(\mathrm{N}\) directly upward?

Short Answer

Expert verified
Each rope exerts approximately 254.35 N.

Step by step solution

01

Understand the Problem

You have two ropes exerting forces on a weight, forming an angle of \(86.0^{\circ}\) between them. Both forces have the same magnitude and their resultant directly pulls the weight upward with a magnitude of 372 N. We need to find the magnitude of the force exerted by each rope.
02

Establish the Equation for Resultant Force

Since the forces are equal and have an angle between them, we can use the law of cosines to determine the resultant force. The equation is set up as follows: \[ R = 2F \cos\left(\frac{\theta}{2}\right) \]where \(R\) is the resultant force (372 N), \(F\) is the magnitude of each force, and \(\theta\) is the angle between forces (\(86.0^{\circ}\)).
03

Solve for the Magnitude of Each Force

Rearrange the equation from step 2 to solve for \(F\):\[ F = \frac{R}{2 \cos\left(\frac{\theta}{2}\right)} \]Substitute the given values:\[ F = \frac{372}{2 \cos\left(\frac{86.0^{\circ}}{2}\right)} \]First, calculate the angle:\( \theta / 2 = 43.0^{\circ} \).Compute \( \cos(43.0^{\circ}) \), and then calculate \( F \).
04

Final Calculation

Calculate:\[ F = \frac{372}{2 \times \cos(43.0^{\circ})} \approx \frac{372}{2 \times 0.7314} \approx \frac{372}{1.4628} \approx 254.35 \text{ N} \]Thus, each rope exerts approximately 254.35 N.

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Key Concepts

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

Law of Cosines
The Law of Cosines is a powerful tool in trigonometry, especially useful when dealing with non-right triangles. It's analogous to the Pythagorean theorem but applies to any triangle shape. This rule helps in finding unknown lengths of sides or angles when certain parameters are known. Here’s the fundamental equation:
  • For any triangle with sides a, b, and c, where angle C is opposite to side c, the law of cosines states: \[ c^2 = a^2 + b^2 - 2ab \cos(C)\]
In the context of force vectors, like in our problem, this law aids in calculating the resultant force when two forces act at an angle to each other. Understanding this relationship allows one to find precise force magnitudes required or their resultant. It’s crucial when tackling problems involving non-perpendicular components.
Resultant Force Calculation
Calculating a resultant force involves understanding how multiple forces combine to produce a single overall effect. The resultant force is essentially the vector sum of all individual forces. In situations where forces are not acting in straight lines, such as those at angles, trigonometric principles like the law of cosines come into play.
In our given problem, knowing that the resultant force is directed straight upward at 372 N provides a starting point. From there, we rearrange the law of cosines to determine the force each rope exerts. Solutions to these problems require detailed equations that accurately reflect each force's direction and magnitude, allowing us to find any missing element once others are known.
Trigonometric Functions
Trigonometric functions are essential in analyzing and resolving forces that operate at angles. Key functions like sine, cosine, and tangent help to express the relationships between angles and sides in a triangle.
  • Cosine, particularly relevant in our problem, gives us the ratio of the adjacent side to the hypotenuse in a right triangle.
For our calculation, we used the cosine function to determine how much of each force contributes to the overall vertical force (372 N). The calculation requires dividing the angle into two equal parts, providing inputs to the cosine function. We use this to rearrange and solve the original equation, helping us understand how different force components sum up to produce a resultant force.
Vector Components
A vector is a quantity having both magnitude and direction, essential in physics to depict quantities like force. When multiple vectors interact, as forces do, they can be broken down into components. These components run along established axes, often seen in horizontal and vertical due considerations.
Forces at angles, such as those in our problem with 86.0° between them, require conversion into components to simplify and solve. These are often accomplished through trigonometric functions:
  • Decomposing each force into parts along the axes allows us to analyze how they contribute to the net force or resultant.
  • This decomposition aids in applying the law of cosines, ensuring vector magnitudes and angles are correctly represented for accurate calculation.
Force Analysis
Force analysis is a critical process in physics required to understand how different forces affect an object. It involves examining the magnitude, direction, and line of action of individual forces and how they interact.
When approaching our exercise, each force's ability to contribute to the upward movement of the weight is scrutinized. Knowing that both forces have equal magnitude and analyzing their effect through angles and components leads us to calculate individual force values accurately.
  • Force analysis helps in recognizing how different forces resolve into a resultant force.
  • With our problem, understanding how the forces work together at an 86° angle aids in precise calculation, granting insights into how changes in magnitude or angle alter outcomes.

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