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A solid cylinder of mass 50 kg and radius 0.5 m is free to rotate about the horizontal .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 accelertion of 2 revolutions s^-2 is?

2
by amru

rope is massless

and it pulled by a force

so tension acts on rope equal to force as it massless by newton's 2nd law

so torque=Tr=Iα

Tr=m(r^2/2)α

T=mrα/2=50(0.5)=25 N