Math Problem Statement

Suppose a 27.6-kg child sits 1.12 m to the left of center on the same seesaw as the problem you just solved in the PRACTICE IT section. A second child sits at the end on the opposite side, and the system is balanced.

Solution

To solve this seesaw problem, we need to calculate the mass of the second child to balance the system.

Assumptions and Approach:

  1. Seesaw's principle: The system is balanced when the sum of torques about the fulcrum is zero.
  2. Torque equation: τ=rF\tau = r \cdot F where rr is the distance from the fulcrum, and FF is the force (equal to the weight of the child: F=mgF = m \cdot g).
  3. The first child, with mass m1=27.6kgm_1 = 27.6 \, \text{kg}, is sitting 1.12m1.12 \, \text{m} to the left of the fulcrum. Thus, their torque is: τ1=m1gr1\tau_1 = m_1 \cdot g \cdot r_1
  4. The second child, with unknown mass m2m_2, is sitting at the end of the seesaw, say at a distance r2r_2 to the right of the fulcrum. Their torque is: τ2=m2gr2\tau_2 = m_2 \cdot g \cdot r_2
  5. Since the system is balanced: τ1=τ2\tau_1 = \tau_2 Simplify to: m1r1=m2r2m_1 \cdot r_1 = m_2 \cdot r_2

Known values:

  • m1=27.6kgm_1 = 27.6 \, \text{kg}
  • r1=1.12mr_1 = 1.12 \, \text{m}
  • r2=distance of the second child to the fulcrumr_2 = \text{distance of the second child to the fulcrum}

Calculation:

Rearrange the torque equation to solve for m2m_2: m2=m1r1r2m_2 = \frac{m_1 \cdot r_1}{r_2}

Please specify the value of r2r_2 (distance of the second child to the fulcrum), so we can compute the result.

Would you like to proceed with details or clarify r2r_2?


Here are 5 related questions:

  1. How does the mass distribution affect the balance of the seesaw?
  2. What happens to the system if one child moves closer to the fulcrum?
  3. How would the calculation change if the seesaw's mass is included?
  4. What is the effect of gravitational acceleration on the balance?
  5. Can the seesaw be balanced if the fulcrum is shifted?

Tip: Always choose the fulcrum as the point of reference when calculating torque—it simplifies the math!

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Math Problem Analysis

Mathematical Concepts

Torque
Equilibrium
Force and Motion

Formulas

Torque equation: τ = r × F
Force: F = m × g
Equilibrium condition: τ1 = τ2
Balance condition: m1 × r1 = m2 × r2

Theorems

Principle of Moments
Equilibrium Conditions

Suitable Grade Level

Grades 8-10