System of Particles and Rotational Motion - Result Question 28

28. A solid cylinder of mass 50kg and radius 0.5 m is free to rotate about the horizontal axis. A massless string is wound round the cylinder with one end attached to it and other hanging freely. Tension in the string required to produce an angular acceleration of 2 revolutions s2 is :

(a) 25N

(b) 50N

(c) 78.5N

(d) 157N

[2014]

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Answer:

Correct Answer: 28. (d)

Solution:

  1. (d) Here α=2 revolutions /s2=4πrad/s2 (given)

Icylinder =12MR2=12(50)(0.5)2=254Kgm2

As τ=Iα so TR=Iα

T=IαR=(254)(4π)(0.5)N=50πN=157N



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