Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
NEET 2017
Exam
NEET
Year
2017
Subject
Physics
Chapter
Laws of Motion

NEET 2017 · Physics · Laws of Motion

A spring of force constant k is cut into lengths of ratio 1: 2: 3 ....

A spring of force constant kk is cut into lengths of ratio 1:2:31: 2: 3. They are connected in series and the new force constant is k′k ′. If now they are connected in parallel and force constant is k′′k ′ ′, then k ' : k ' ' is

Options

  1. A1:61: 6
  2. B1:91: 9
  3. C1:111: 11
  4. D1:141: 14

Correct answer

C. 1:111: 11

Step-by-step solution

Spring constant ∝1length∝ \dfrac{1}{length}

k∝1lk ∝ \dfrac{1}{l},
Spring constant for the length ratios are k1=6k{k}_{1} = 6k

k2=3k{k}_{2} = 3k

k3=2k{k}_{3} = 2k

In series connection of springs,

1k′=16k+13k+12k\dfrac{1}{{k}^{′}} = \dfrac{1}{6k} + \dfrac{1}{3k} + \dfrac{1}{2k}

1k′=66k\dfrac{1}{{k}^{′}} = \dfrac{6}{6k}

k′=k{k}^{′} = k.

In parallel connection of springs,

k′′=6k+3k+2k{k}^{'′} = 6k + 3k + 2k

k′′=11k{k}^{′′} = 11k

k′k′′=111\dfrac{{k}^{′}}{{k}^{′′}} = \dfrac{1}{11}

i.e., k′:k′′=1:11{k}^{′}: {k}^{′′} = 1: 11
Practice Laws of Motion on Quantrex Academy →

More from Laws of Motion

The magnitude and direction of the acceleration produced in a body of mass 5 kg when two… NEET 2026A box of mass 15 kg is kept on the floor of a stationary trolley. The coefficient of… NEET 2026A car travels on a circular racetrack of radius 50 m, which is banked at an angle θ . If… NEET 2026There are two inclined surface of equal length (L) and same angle of inclination 45^ ∘… NEET 2025A uniform rod of mass 20 kg and length 5 m leans against a smooth vertical wall making an… NEET 2025A box of mass 5 kg is pulled by a cord, up along a frictionless plane inclined at 30^ ∘… NEET 2024A bob is whirled in a horizontal circle by means of a string at an initial speed of 10… NEET 2024A horizontal force 10 N is applied to a block A as shown in figure. The mass of blocks A… NEET 2024 Full Laws of Motion list All NEET PYQs