The twisting coupleper unittwistfor a solid cylinder of radius 3 cm is 0.1 Newton-meter.The twistingcouple per unit twist, for a hollow cylinder of same material with outer and inner radii 5 cm and 4 cm respectively, will be

The twisting coupleper unittwistfor a solid cylinder of radius 3 cm is

1.	The twisting coupleper unittwistfor a solid cylinder of radius 3 cm is 0.1 Newton-meter.The twistingcouple per unit twist, for a hollow cylinder of same material with outer and inner radii 5 cm and 4 cm respectively, will be
Answer» 0.1 NEWTON - METER 0.455 Newton - meter 0.91 Newton - meter 1.82 Newton - meter Solution :Twisting couple per unit twist for solid cylinder `C_(1)=(PI eta r^(4))/( 2l)` Hollow cylinder `C_(2)=(pi eta (r_(2)^(4) -r_(1)^(4)))/(2l)` `therefore C_(2)=C_(1)(r_(2)^(4)-r_(1)^(4))/(r^(4)) =(0.1xx(625-256)xx10^(-8))/( 81xx10^(-8))` `(36.9)/(81)=0.455` Newton-meter