Math Problem Statement

  1. The two ends of a 20-m rope are fastened at two points on the ceiling, 12 m from each other. If a load of 200 kg is placed at the center of the rope, find the tension in the rope.

Solution

This problem involves solving for the tension in a rope subjected to a load in the center. Here's how we approach it:

Given:

  • The rope's total length: L=20mL = 20 \, \text{m}
  • The distance between the points where the rope is fastened: D=12mD = 12 \, \text{m}
  • Load: m=200kgm = 200 \, \text{kg}
  • Gravitational acceleration: g=9.8m/s2g = 9.8 \, \text{m/s}^2
  • Force due to load: F=mg=200×9.8=1960NF = mg = 200 \times 9.8 = 1960 \, \text{N}

Assumptions:

  • The load is placed at the midpoint of the rope, so the vertical displacement will cause the rope to form two symmetric segments.
  • We assume the tension is the same in both segments of the rope.
  • We need to find the vertical displacement of the rope caused by the load to calculate the angle at which the tension acts.

Step 1: Geometry of the Rope

The horizontal distance between the attachment points is 12 m, and the rope is 20 m long. Each side of the rope will form a right triangle with:

  • Half of the horizontal distance: 6m6 \, \text{m}
  • The vertical distance: hmh \, \text{m} (the drop in the center due to the load)

The length of each half of the rope is 10m10 \, \text{m}. Using the Pythagorean theorem: 102=62+h210^2 = 6^2 + h^2 100=36+h2100 = 36 + h^2 h2=64h^2 = 64 h=8mh = 8 \, \text{m} Thus, the vertical drop due to the load is 8 meters.

Step 2: Forces Acting on the Rope

The tension in each half of the rope, TT, acts at an angle θ\theta with the horizontal. The vertical components of the tension must balance the weight of the load, and the horizontal components must cancel out.

The angle θ\theta can be found from: θ=tan1(h6)=tan1(86)53.13\theta = \tan^{-1} \left( \frac{h}{6} \right) = \tan^{-1} \left( \frac{8}{6} \right) \approx 53.13^\circ

Step 3: Balance of Forces

The vertical components of the tension add up to balance the weight of the load: 2Tsin(θ)=1960N2T \sin(\theta) = 1960 \, \text{N} Thus: T=19602sin(53.13)=19602×0.798619601.59721227.5NT = \frac{1960}{2 \sin(53.13^\circ)} = \frac{1960}{2 \times 0.7986} \approx \frac{1960}{1.5972} \approx 1227.5 \, \text{N}

Final Answer:

The tension in the rope is approximately 1227.5N1227.5 \, \text{N}.

Would you like more details or have any questions?


Here are 5 related questions for further exploration:

  1. What would the tension be if the distance between the fastening points were increased to 15 meters?
  2. How does the tension change if the load is moved away from the center?
  3. How would the tension change if the load were increased to 300 kg?
  4. What happens to the tension if the rope length is shortened by 2 meters?
  5. How would the tension be affected if the gravitational acceleration were different (e.g., on another planet)?

Tip: Always verify the geometry of the system when dealing with tension problems, as angles play a crucial role in determining forces.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Statics
Pythagorean Theorem
Forces

Formulas

Pythagorean theorem: a^2 + b^2 = c^2
Force due to gravity: F = mg
Tension force balance: 2T sin(θ) = F

Theorems

Pythagorean Theorem
Trigonometric Functions (sin, cos, tan)

Suitable Grade Level

Undergraduate Physics or Advanced High School (Grades 11-12)