Start Learning Free

Before You Begin

Question #42787

Difficulty: 8/10 | 🟢 Free

The Question

An infinite mechanical ladder network is constructed using massless springs, analogous to an infinite capacitor ladder. The network consists of nodes numbered n=0,1,2,…,∞n = 0, 1, 2, \dots, \infty. For each n≥1n \ge 1, a series spring of stiffness k1=6kk_1 = 6k connects node n−1n-1 to node nn, and a shunt spring of stiffness k2=kk_2 = k connects node nn to a fixed rigid wall. A constant static force FF is applied at node 0, and the system is allowed to reach static equilibrium. Let Us1U_{s1} be the elastic potential energy stored in the first series spring (between node 0 and node 1), and Up,∞U_{p,\infty} be the total elastic potential energy stored in all the shunt springs combined. What is the ratio Us1Up,∞\frac{U_{s1}}{U_{p,\infty}}?

Options

  • A.

    56\frac{5}{6}

  • B.

    23\frac{2}{3}

  • C.

    32\frac{3}{2}

  • D.

    13\frac{1}{3}

Check Your Answer

Correct Answer

Step-by-Step Solution

Explanation

How the Examiner Thinks

Multi-Concept_Bridge

Master problems that require linking physics and math concepts to solve complex competitive questions.

Concepts Behind This Question

Infinite Series Capacitance|Effective Spring Constant|Energy Partitioning

Why This Question Is Tricky

Common Mistakes

This question tests the student's ability to map an infinite capacitor ladder to a mechanical spring system and correctly evaluate the spatial distribution of potential energy.

A common trap (Energy Equipartition Logic) is assuming that the total energy is equally partitioned between the series and shunt components (Up,∞=Utot/2U_{p,\infty} = U_{tot}/2), which leads to the incorrect ratio of 2/3.

Another trap is ignoring the infinite series and only comparing the first stage energies, leading to 3/2.

Students must recognize that force (analogous to charge) attenuates geometrically across the nodes, requiring an infinite geometric sum of the energy density to find the true total shunt energy.

Quick Facts About This Question

Question Information

SubjectPhysics
ChapterElectrostatic Potential and Capacitance - Class 12
ConceptInfinite Series Capacitance
Difficulty8
Cognitive Load7
Target Solve Time160 sec
AccessFree