A ring of radius 0.5 m and mass 10 kg is rotating about its diameter with angular velocity of 20 rad/s. Its KE is :-

Options

A. 10J
B. 100J
C. 500J
D. 250J

Answer

D

Explanation

`K.E.=(1)/(2)lomega^(2)`
`l_("about diameter")=(MR^(2))/(2)`
`therefore K.E.=(1)/(2)((MR^(2))/(2))omega^(2)`
`=(1)/(2)xx(10xx0.5xx0.5)/(2)xx400`
`=250J`.