The rotational kinetic energy of a body is E. In the absence of external torque, the mass of the body is halved and its radius of gyration is doubled. Its rotational kinetic energy isA. 2 EB. E/2C. ED. E/4

The rotational kinetic energy of a body is E. In the absence of extern

1.	The rotational kinetic energy of a body is E. In the absence of external torque, the mass of the body is halved and its radius of gyration is doubled. Its rotational kinetic energy isA. 2 EB. E/2C. ED. E/4
Answer» Correct Answer - B `I_(1)omega_(1)=I_(2)omega_(2)` if no ecternal torqe acts on the system total angular momentum remains constant. `I_(1)=m_(1)K_(1)^(2) " " I_(2)=m_(2)K_(2)^(2)` `(I_(1))/(I_(2))=(m_(1))/(m_(2))(K_(1)^(2))/(K_(2)^(2))=2xx(1)/(4)=(1)/(2)` `therefore I_(2)=2I_(1)` `therefore omega_(2)=(I_(1)omega_(1))/(I_(2))=(I_(1)omega_(1))/(2I_(2))=(omega_(1))/(2)` `(KE_(1))/(KE_(2))=(I_(1))/(I_(2))xx((omega_(2))/(omega_(1)))^(2)` `=(1)/(2)xx4=2`

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The rotational kinetic energy of a body is E. In the absence of external torque, the mass of the body is halved and its radius of gyration is doubled. Its rotational kinetic energy isA. 2 EB. E/2C. ED. E/4

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