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STD 11 - 4.1. newtons laws of motion — NEET STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceNEETSTD 11 - 4.1. newtons laws of motion4 Marks
Question
An elevator accelerates upwards at a constant rate. A uniform string of length $L$ and mass $m$ supports a small block of mass $M$ that hangs from the ceiling of the elevator. The tension at distance $l$ from the ceiling is $T$ . The acceleration of the elevator is
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Answer

Let $a$ be the acceleration of the lift Mass of lower portion of string

$=\frac{m}{L}(L-l)$

$\therefore T-M g-\frac{m g}{L}(L-l)=\left(M+\frac{m}{L}(L-1)\right) a$

$\therefore a=\frac{T}{M+m-\frac{m l}{L}}-g$

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