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GATE 2016 ME (ME3) – Question 40

Engineering Mechanics · Kinematics and dynamics of rigid bodies in plane motion · 2 marks · Numerical answer

An inextensible massless string goes over a frictionless pulley. Two weights of 100 N and 200 N are attached to the two ends of the string. The weights are released from rest, and start moving due to gravity. The tension in the string (in N) is ______.

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Correct answer: 130 to 135

Explanation

For weights W₁=100N,W₂=200N, write T−W₁=(W₁/g)a and W₂−T=(W₂/g)a. Eliminating a gives T=2W₁W₂/(W₁+W₂)=**133.333N**. The two tensions are equal for a massless rope and frictionless massless pulley.