Math Problem Statement

The two ropes seen in (Figure 1) are used to lower a 255 kg piano 5.30 m from a second-story window to the ground. How much work is done by each of the three forces?

The two ropes seen in the figure are used to lower a 255 kg piano 5.30 m from a second-story window to the ground. How much work is done by each of the three forces?

Solution

To calculate the work done by each of the three forces on the piano, we will need to use the following information from the diagram and apply the work formula:

Formula for Work:

W=Fdcos(θ)W = F \cdot d \cdot \cos(\theta) Where:

  • FF is the force applied,
  • dd is the displacement of the object (5.30 m, in this case),
  • θ\theta is the angle between the force and the displacement.

Forces in the Diagram:

  • T1=1830NT_1 = 1830 \, \text{N} (at 6060^\circ),
  • T2=1295NT_2 = 1295 \, \text{N} (at 4545^\circ),
  • Gravitational Force, FG=2500NF_G = 2500 \, \text{N}, directed straight downward.

Since the piano is being lowered directly downward by 5.30 m, we calculate the work done by each force using the displacement and the angle between the force and the displacement.

Let me calculate the work done by each of the three forces.

Step 1: Work done by gravity

For gravity, the force is already vertical and aligned with the displacement, so θ=0\theta = 0^\circ and cos(0)=1\cos(0^\circ) = 1.

WG=2500N5.30mcos(0)W_G = 2500 \, \text{N} \cdot 5.30 \, \text{m} \cdot \cos(0^\circ) WG=25005.301W_G = 2500 \cdot 5.30 \cdot 1

Step 2: Work done by T1T_1 (Tension in the first rope)

For T1T_1, the angle between the force and the direction of displacement is 6060^\circ, so we will use cos(60)=0.5\cos(60^\circ) = 0.5.

WT1=1830N5.30mcos(60)W_{T_1} = 1830 \, \text{N} \cdot 5.30 \, \text{m} \cdot \cos(60^\circ) WT1=18305.300.5W_{T_1} = 1830 \cdot 5.30 \cdot 0.5

Step 3: Work done by T2T_2 (Tension in the second rope)

For T2T_2, the angle between the force and the direction of displacement is 4545^\circ, so we will use cos(45)=220.707\cos(45^\circ) = \frac{\sqrt{2}}{2} \approx 0.707.

WT2=1295N5.30mcos(45)W_{T_2} = 1295 \, \text{N} \cdot 5.30 \, \text{m} \cdot \cos(45^\circ) WT2=12955.300.707W_{T_2} = 1295 \cdot 5.30 \cdot 0.707

I will calculate each of these values next.It seems like I can’t do more advanced data analysis right now. Please try again later.

In the meantime, if you'd like to manually calculate the results, here are the steps:

  1. Work done by gravity: WG=2500N5.30m=13,250JW_G = 2500 \, \text{N} \cdot 5.30 \, \text{m} = 13,250 \, \text{J}

  2. Work done by T1T_1: WT1=1830N5.30mcos(60)=18305.300.5W_{T_1} = 1830 \, \text{N} \cdot 5.30 \, \text{m} \cdot \cos(60^\circ) = 1830 \cdot 5.30 \cdot 0.5 This will give WT1=4849.5JW_{T_1} = 4849.5 \, \text{J}.

  3. Work done by T2T_2: WT2=1295N5.30mcos(45)=12955.300.707W_{T_2} = 1295 \, \text{N} \cdot 5.30 \, \text{m} \cdot \cos(45^\circ) = 1295 \cdot 5.30 \cdot 0.707 This will give WT2=4859.3JW_{T_2} = 4859.3 \, \text{J}.

Let me know if you need further details or have any questions!


Here are some follow-up questions you might consider:

  1. How do the angles of tension affect the work done by each rope?
  2. What would happen if the piano were lowered with only one rope?
  3. Can you think of any scenario where the work done by a force would be zero?
  4. How does gravity influence the direction of motion in this case?
  5. What would the result be if the tension forces were applied horizontally?

Tip: Always double-check the direction of forces when calculating work to ensure the correct use of cosine for the angle.

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Math Problem Analysis

Mathematical Concepts

Work
Forces
Tension
Trigonometry
Vectors

Formulas

W = F * d * cos(θ)
W_G = 2500 N * 5.30 m * cos(0°)
W_T1 = 1830 N * 5.30 m * cos(60°)
W_T2 = 1295 N * 5.30 m * cos(45°)

Theorems

Work-Energy Theorem
Trigonometric Identity

Suitable Grade Level

Grades 11-12