Math Problem Statement

The figure shows a three-particle system, with masses m1 = 3.3 kg, m2 = 4.9 kg, and m3 = 6.4 kg. What are (a) the x coordinate and (b) the y coordinate of the system’s center of mass?

Solution

To find the coordinates of the center of mass of the system, we use the following formulas for the center of mass in the x- and y-directions:

xcm=miximix_{cm} = \frac{\sum m_i x_i}{\sum m_i} ycm=miyimiy_{cm} = \frac{\sum m_i y_i}{\sum m_i}

Where mim_i are the masses and xix_i, yiy_i are their corresponding coordinates.

From the figure:

  • m1=3.3kgm_1 = 3.3 \, \text{kg}, at (x1,y1)=(1,0)(x_1, y_1) = (1, 0)
  • m2=4.9kgm_2 = 4.9 \, \text{kg}, at (x2,y2)=(2,1)(x_2, y_2) = (2, 1)
  • m3=6.4kgm_3 = 6.4 \, \text{kg}, at (x3,y3)=(0,3)(x_3, y_3) = (0, 3)

Step 1: Calculate xcmx_{cm}

xcm=(3.3×1)+(4.9×2)+(6.4×0)3.3+4.9+6.4=3.3+9.8+014.6=13.114.60.90mx_{cm} = \frac{(3.3 \times 1) + (4.9 \times 2) + (6.4 \times 0)}{3.3 + 4.9 + 6.4} = \frac{3.3 + 9.8 + 0}{14.6} = \frac{13.1}{14.6} \approx 0.90 \, \text{m}

Step 2: Calculate ycmy_{cm}

ycm=(3.3×0)+(4.9×1)+(6.4×3)3.3+4.9+6.4=0+4.9+19.214.6=24.114.61.65my_{cm} = \frac{(3.3 \times 0) + (4.9 \times 1) + (6.4 \times 3)}{3.3 + 4.9 + 6.4} = \frac{0 + 4.9 + 19.2}{14.6} = \frac{24.1}{14.6} \approx 1.65 \, \text{m}

Thus, the coordinates of the center of mass are:

  • xcm0.90mx_{cm} \approx 0.90 \, \text{m}
  • ycm1.65my_{cm} \approx 1.65 \, \text{m}

Would you like further clarification on any of these steps?


Related Questions:

  1. What happens to the center of mass if all the particles have the same mass?
  2. How would you find the center of mass for a system with more than three particles?
  3. How do the coordinates of the individual masses influence the center of mass position?
  4. Can the center of mass ever lie outside the physical system of particles?
  5. How does the center of mass change if the coordinate system is shifted?

Tip: The center of mass represents the average position of mass distribution in a system and can simplify the analysis of motion in complex systems.

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Math Problem Analysis

Mathematical Concepts

Center of Mass
Physics
Coordinate Geometry

Formulas

x_cm = (sum of m_i * x_i) / (sum of m_i)
y_cm = (sum of m_i * y_i) / (sum of m_i)

Theorems

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Suitable Grade Level

High School Physics