Two blocks of masses m and M are attached to the two ends of a light string passing over a fixed ideal pulley (M gg m). When the blocks are in motion, the tension in the string is approximately

Question

Two blocks of masses m and M are attached to the two ends of a light string passing over a fixed ideal pulley (M gg m). When the blocks are in motion, the tension in the string is approximately (A) (M-m) g (B) m g (C) 2 mg (D) ((m/M)) m g

Tardigrade Admin · Accepted Answer

Let a be the common acceleration of the system and T be the tension in the string. The equation of motion for the block m is T-m g=m a ldots (i) The equation of motion for the block M is M g-T=M a ldots (ii) Adding (i) and (ii), we get M g-m g=m a+M a or a=((M-m/m+M)) g <img class="img-fluid question-image" alt="image" src="https://cdn.tardigrade.in/img/question/physics/708d1d846bf3fa916689fcbd5632dc00-.png" /> Substituting this value in (i), we get T=(2 M m/M+m) g ∵ M gg m, m can be neglected as it is very small when compare to M ∴ T ≈ 2 m g

Q. Two blocks of masses $m$ and $M$ are attached to the two ends of a light string passing over a fixed ideal pulley $(M ≫ m)$ . When the blocks are in motion, the tension in the string is approximately

$(M - m) g$

$m g$

$2 m g$

$(\frac{m}{M}) m g$

Q. Two blocks of masses m and M are attached to the two ends of a light string passing over a fixed ideal pulley (M≫m). When the blocks are in motion, the tension in the string is approximately

(M−m)g

mg

2mg

(Mm​)mg

Q. Two blocks of masses $m$ and $M$ are attached to the two ends of a light string passing over a fixed ideal pulley $(M ≫ m)$ . When the blocks are in motion, the tension in the string is approximately

$(M - m) g$

$m g$

$2 m g$

$(\frac{m}{M}) m g$