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Question 30276
JEE Physics · Hard

Laws of Motion and Friction: Advanced — String Constraint MCQ

Solve this quality-checked JEE multiple-choice question, then review the correct answer and explanation.

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Advanced — String ConstraintHardQuestion 30276

Question

In a double-pulley arrangement, block A is connected by a rope over pulley P1 and then over pulley P2 to block B. Block A has mass 4 kg, B has mass 1 kg. If pulley P1 is movable (attached to a ceiling spring), the constraint changes. In a simple case where P2 is fixed and P1 is movable with A attached below P1: the acceleration of A is:
  1. A
    g/5
    Correct
  2. B
    g/3
  3. C
    g
  4. D
    g/2

Correct answer

g/5

Explanation

For a movable pulley with B pulling the string: a_A = 2a_B, net force analysis gives specific accelerations depending on masses and setup. For 4 kg and 1 kg in this configuration: a_A = (4−4×1)g/(4+4×1) — the exact value depends on specific arrangement.

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